US2079572A - Method of and apparatus for recording sound on the edge of film - Google Patents

Description

J. R. JKIEL METHOD OF AND APPARATUS FOR RECORDING SOUND ON THE EDGE OF FILM Filed Jan. 5, 1933 5 Sheets-Sheet l May 4,. 1937. 2,079,572

METHOD or AND APPARATUS FOR RECORDING SOUND on THE EDGE OF FILM ,1. R. KIEL 5 Sheets-Sheet 2 Filed Jan. 5, 1953 J. R. KIEL May 4, 1937. 2,079,572 METHOD OF AND APPARATUS FOR RECORDING SOUND ON THE EDGE OF FILM Filed Jan. 3, 1955 5 SheetsSheet 3 May 4, 1937.

J. R. KIEL 2,079,572

METHOD OF AND APPARATUS FOR RECORDING SOUND ON THE EDGE OF FILM 5 Sheets-Sheet 4 J. R. KIEL May 4, 1937.

METHOD OF AND APPARATUS FOR RECORDING SOUND ON THE EDGE OF FILM 1955 5 Sheets-Sheet 5 Filed Jan. 3,

Z 3 3 w z z i Patented May 4, 1937 PATENT OFFICE METHOD OF AND APPARATUS FOR RECORD- ING SOUND ON THE EDGE OF FILM John Ripley Kiel, Chicago, Ill., assignor to Ripley Corporation, Chicago, Ill., a corporation of I111- nois Application January 3, 1933, Serial No. 649,865

Claims.

This invention relates to a method of and apparatus for recording sound on the edge of a motion picture film, and to the sound film produced thereby.

An object of this invention is to provide a method of and apparatus for successfully record ing sound on the edge of a motion picture film, and particularly a method which can be used on old motion picture films.

Another object is to provide means for adjusting the drive mechanism to correct for shrinkage of the film having sound thereon, so as to cause the film to run smoothly at the point where the reproducer pick-up is applied to the film to I reproduce sound therefrom, or at the point where sound is to be recorded thereon.

These and other objects, as will hereinafter appear, are accomplished by this invention which is fully described in the following specification and shown in the accompanying drawings, in which- Figure 1 is a front elevation of the mechanism for trimming the film and for recording sound thereon;

Fig. 2 is an enlarged partial section on the line 2 of Fig. 1;

Fig. 3 is an enlarged detail of the roller over which the film is drawn while being trimmed;

Fig. 4 is a partial enlarged section on the line 4 of Fig. 1;

Fig. 5 is an enlarged detail of the film at the instant of passing under the trimming knife;

Fig. 6 is a partial enlarged section on the line 6 of Fig. 1 showing the recording mechanism;

Fig. 7 is an enlarged detail of the rollers for gripping the master record strip at the instant sound is recorded thereon;

Fig. 8 is a partial section on the line 8 of Fig. 7

Figs. 9 and 10 are enlarged details of the film while being trimmed at the two points shown in Fig. l;

Fig. 11 is a partial enlarged section on the line ||-ll of Fig. 7;

Fig. 12 is a partial plan view of Fig. 1 showing the driving mechanism;

Fig. 13 is. an enlarged side elevation showing the drive sprocket of Fig. 1 with means for adjusting to accommodate for the shrinkage of the film due to age;

Fig. 14 is a section on the line |4-|4 of Fig. 13;

Figs. 15 and 16 are partial enlarged views illustrating different positions of adjusting mechanism;

Fig. 17 is a partial enlarged view on the line I! of Fig. 6 showing the recording tool in the operation of making a record on the edge of the film;

Fig. 18 is a partial transverse section of the film on the line 18 of Fig. 17;

Fig. 19 is a diagrammatic View of the motion picture camera and of the sound recording mechanism driven in synchronism;

Fig. 20 is a diagrammatic view of the mechanism for re-recording on a finishedmotion picture film from the master record strip;

Fig. 21 is a partial diagrammatic view of the mechanism for projecting a picture, and for reproducing sound from the edge of the same film;

Fig. 22 is a partial enlarged section on the line 22 of Fig. 21;

Fig. 23 is a reduced elevation on the line 23 of Fig. 22;

Fig. 24 is an enlarged section on the line 24 of Fig. 21; and

Fig. 25 is a longitudinal section through a pickup device.

In general, my method of recording and reproducing comprises simultaneously taking a picture and making a master record on the edge of a separate record strip, and re-recording the sound on the edge of the finished positive motion picture film so that the picture can be projected and the sound picked up in synchronism.

My method of recording sound on the edge of a film is particularly applicable to recording on films now extant where the sound does not necessarily have to be in synchronism with the picture.

The method of recording sound on the edge of a master record strip which is preferably a film such as is used in motion picture projectors, but which for this purpose may have no emulsion thereon. This film is fed through the recording mechanism shown in Figs. 1 to 19.

Referring to Figs. 1 and 19, the master record strip A is passed through edge trimmers B and 4 C which are preferably two or more in number, after which it passes to the recording device D, and thence to the reel F. The motor G for driving this recording mechanism and the motor H for driving the motion picture camera I are synchronous motors, and are driven from the same alternating current circuit, and both motors are under control of a single operating switch. Thus by throwing in this switch, both the motion picture camera and the sound recording mechanism are started simultaneously and are maintained in synchronism.

In order to fix the points at which the master record strip and the motion picture film start when the recording mechanism has been first set in motion, an operator steps in front of the camera and claps two boards together, the act and the sound being recorded simultaneously on the motion picture film and on the record strip. Thus by setting the projector and the pick-up together at these two points on the finished film, the sound is reproduced and the picture as projected will be in synchronism.

Referring now to Fig. 1, the sound recording mechanism is mounted on a frame to which is secured the synchronous motor G, which has a shaft St to which is keyed a worm 32 (Fig. 12) which meshes with a worm wheel 33 on a shaft 34, to which is keyed a drive sprocket 35, shown enlarged in Figs. 13 to 16. The film A passing over this sprocket is drawn through the trimming and recording mechanism, as will now be described. The shaft 34 has a bevel gear 38 keyed thereon which meshes with a gear 3'! on the vertical shaft 38, which in turn carries a bevel gear 39 which meshes with a gear 40 on a shaft 4|. The shaft ll'serves to drive the sprockets, which will later be described, which pull the film A through the trimmers and it also serves to oscillate the trimmers.

In front of the shaft 34 is a shaft 42 (Figs. 1 and 11) which carries a roller 43 having two corrugated faces 44 which are also preferably roughened slightly so as to cause them to grip the film A between its face, and that of the pressure roller 45, the latter being carried upon a bell crank 46 which has an extension 47 (Figs. 7 and 11) surrounding the center of the roller 45, the bell crank being hingedly mounted at 48 and normally urged toward the roller 43 by means of a spring 49, or the like. An idler roller 50 (Fig. 8) bears upon the underside of the roller 43 and is spring-pressed, and is eccentrically mounted at 5!. The roller 50 has a disk 50 with an outwardly flared edge pressed inwardly by a spring 50 which bears against a screw head 50. Thus the film is held firmly against a flange 43 on the roller 43.

Referring again to Fig. 11, the roller 43 is undercut at 43 and is provided with the shoulder flange 43 which forms an abutment against which the film A rests while held firmly gripped as it passes between the rollers 43 and 45. A sound recording tool 52, which will later be described, and which is carried by the recording device D, bears against the outer edge of the film at the point of maximum pressure of the roller 45. For this purpose the edge of the film, which has previously been trimmed, extends beyond the rollers a matter of .002" or .003. Before reaching this recording device, however, the film passes through one or more trimmers as B, C. To do this the film passes first around a shouldered roller 53 (Figs. 1 and 3) against which the film A is pressed by means of a roller 54 which is carried on one arm of a bell crank 55 fulcrumed at 56, and pulled down by means of a spring 57. A lever-operated cam 58 serves to lift the roller 54 against the action of the spring 51. An idler roller 58 is carried on an arm 60, and the idler roller is pressed against the film A by means of a spring 8|. The film is firmly held against the back of the roller by a spring-pressed disk 59, similar to the disk 50 Immediately in front of the shouldered roller 53 is a knife blade 62 which is firmly secured to an arm 03, as shown in detail in Fig. 2, the arm being pivotally mounted at 64, and held in operative position by a spring 55. The arm 63 is provided with a screw 66 whereby the distance of the cutting edge of the blade 62 from the roller can be nicely adjusted. As the film A passes up under the blade 62 a fine shaving 61 is cut away, as shown in Fig. 5. The two arms 63 are mounted upon a reciprocating block 68 which is slidably mounted upon guides 89, 10 which are secured to the frame 30. This frame carries a stud H upon which is journaled a worm wheel 12 which meshes with a worm 13 on the shaft 4|. On the face of the worm wheel 12 is formed a cam groove 14 in which operates a pin 15 which is carried by the reciprocating block 68, so that as the worm wheel 12 rotates the block 68 is propelled back and forth with a reciprocating motion, which is preferably substantially uniform in both directions. A suction pipe C draws off shavings cut from the film.

For this purpose I prefer to use a safety razor blade, and I have found that by mounting and reciprocating it in this way I am able to trim between 1000 and 1500 feet of film without resharpening it where the blade used is of superior quality. It is necessary for good results to trim the edge, owing to the fact that the edge of the film as ordinarily used is quite rough and all of its inequalities would combine with the record on the edge of the film, thereby introducing all sorts of noises unless the edge of the film were trimmed before the record was made thereon.

In Fig. 9 the edge film A is shown quite rough.

As the result of the first cut the edge A is much smoother, but is still somewhat rough. The second cut leaves a surface A of Fig. 10 which is very much smoother. Under some circumstances one cut would be insufficient, while under others two or even three cuts mights be necessary. Each cut when properly made tends to leave the surface in better condition than the one before it. Each of the cutters is provided with a driving sprocket 16, as shown in Fig. 4, which is driven from the 1 shaft 4|.

In Fig. 6 is shown the recording tool and the recording device in which it is used. This device comprises a hollow iron housing 71, an iron core 18 preferably screwed therein, the housing having an iron cover 19 secured thereto and loosely surrounding the free end of the core 18 so as to provide an annular air gap 80. In this gap is located a sleeve 8| about which is wound a voice coil 82 which is adapted to operate in substantially the same way as the voice coils of dynamic loud speakers. The sleeve 8| is mounted upon a disk 83 which is secured to a movable member 84, the outer end of which is carried by a spring steel member 85 which is secured to a spider 86 which in turn is secured to the cover I9. The sleeve 81 is guided by a fiber member 81, which in turn is secured at two opposite points to the spider 86, or the like. A magnet coil 88 surrounds the core 18, and is energized by a direct current from a suitable source.

Thus it will be seen that with the magnet energized the voice coil Bl will be suspended in a strong magnetic field. I have found, however, that it is necessary to control the movement of the member 84 as it has a tendency to move through too great an amplitude. For this reason I have provided a means for damping the movement of the members 84. To do this I have provided rubber pads 89, 90, or other suitable damping means, on the two sides of the disk 83 while the core 18 is adjustable toward and from the pad 90 by turning the threaded core 18 in the housing 11. A look nut l8 is provided for locking the core in the adjusted position.

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I have also found it preferable to use additional damping means consisting of rubber pads 9|, 92, or other suitable material, lying on each side of a flange 93 on the member 84. Adjustment of this damping means is provided in the way of a threaded collar 94 which is screw-threaded into the center of the spider 86. The member 84 is drilled and reamed to receive a recording tool 95 which carries a recording point 95, preferably a diamond ground to a point substantially asshown in Fig. 1'7. This point is substantially chisel-shaped, the end of the chisel being viewed in Fig. 17, and having sides which lie at an angle of about 80 toeach other, the point being rounded with a radius of approximately .001".

As shown in Fig. 17, the film A is forced along beneath the recording point 96, thereby slightly propelling the edge of the film beneath the smooth face of the diamond point so as to make it slightly T-shaped in cross section, as shown in Fig. 18. If at the same time a current of varying strength is passed through the voice coil 82 of the recording device, a vibratory motion will be imparted to the point 96, and a wavy record, as shown in Fig. 17, will be formed in the edge of the film. This same edge can later be used to reproduce the same pitch of tone as that originally imparted to it by passing the film under a suitable electrical pick-up device, which is vibrated at the same rate as the waves thus formed in the edge of the film A. This device (Fig. is preferably of the voice coil type, somewhat like the recording device of Fig. 6 but of very light construction, so that movement of the voice coil in its magnetic field sets up small electric currents which can be amplified.

To prevent possible damage to the diamond point in case the film were to break or the end of it were to pass the roller 43 (Fig. '7), I have provided a safety device in the form of a finger 91 which bears upon the film A, and which forms part of a bell crank which is pivotally mounted at 98. The other end of the bell crank carries a mercury switch 99 which is connected in series with the voice coil. Thus the instant the end of the film no longer supports the finger 91, it will be forced inwardly into the space 43 of Fig. 11, thereby breaking the mercury switch 99 and bringing the voice coil to rest. It can also be connected in such a way as to stop the camera, or it may actuate an alarm or signal to show the end of a film. In order to insure smoothness of operation of the record strip at the point where the recording is done, I have provided the shaft 42 with a fly wheel 42* and prefer to mount the shaft 42 in ball bearings, as shown in Fig. 11.

It is very essential that the film A in passing over the sprocket (Figs. 13 to 16 inclusive) do so as smoothly as possible. Where the film has shrunk, however, particularly in the case of 16 millimeter film, the jerkiness produced by the film slipping as it passes over the sprocket teeth causes an irregular motion of the film which produces a flutter in the sound generated, which is very annoying. This is particularly true in the ease of the small films for the reason that the distance between the holes in the small film is actually greater than that of the larger film, and this coupled with the fact that the smaller film is traveling at a very much slower rate greatly exaggerates any slight error that might occur in the distance between the holes in the film.

To overcome this difiiculty I have cut away the center of the sprocket 35 and mounted therein two spaced adjustable members I00 which are carried by a plunger IOI which rests upon a screw I02. Plates I03 of the same height and curvature as the members I00 are secured to the plunger IOI by means of rivets I04, so that they move up and down together. Facing the members I00 and the plates I03 is a spring-pressed shoe I05 which rests upon the film A and holds it in contact with the plates. Thus it will be seen that by adjusting these plates in and out a point will be reached where the distance between sprocket teeth is equal to the distance between sprocket holes, and the film will pass on and ofi the sprocket smoothly. and the flutter from this source will be eliminated.

Having made a master record strip which is entirely separate and distinct from the motion picture film with which it is in synchronism, the motion picture film negative is developed and printed in the usual way, after which a sound. record from the master record strip is imparted thereto. It will also be apparent that a disk record may be made and used instead of the record strip shown, and the sound record on the disk may be re-recorded on the edge of the motion picture film by driving the disk record and the motion picture film in synchronism in much the same way as that shown in Fig. 20, care being taken to see that the sound and action are properly synchronized.

In this the record strip J made as previously shown and described is led off a reel I05 and through a suitable electric sound pick-up device I01 of a suitable electrical type, and thence to a reel I08. One or more positive motion picture films K, L, are then each threaded into a recording mechanism of the type shown in Fig. l, and set in synchronism with the master sound record J. The sound pick-up I0! is then connected with a suitable amplifier I09 and the output current from this is connected to a recording device D of Fig. l. Synchronous motors then serve to drive the master record strip J and the motion picture films K and L, and since these motors are all connected to the same alternating circuit source they will remain in synchronism so that the sound record on the master record strip J will be transferred to the edge of the films K, L, etc. While only two motion picture films are thus shown in the process of being treated, it will be understood that sound can thus be simultaneously recorded on several of them.

The sound thus recorded on the edge of the motion picture film can be picked up, amplified and reproduced in suitable apparatus, as shown in Fig. 21. In this case the motion picture film M with the sound recorded on its edge is passed through a motion picture projector N, which is driven by means of a suitable motor 0. The film then passes to a sound pick-up device P which has two guides H9 and III between which the film M passes. A stylus I I2 of the reproducing pick-up (Fig. 25) engages the sound record on the edge of the film, and this is connected to suitable electric apparatus so that the motion of the film is transmitted to this apparatus as an undulating electric wave. This is then amplified and passed to a loud speaker in the usual way.

The pick-up as shown in Fig. 25 comprises a stylus II2 having a chisel-edged diamond at its end adapted to bear against the sound record edge of a film A, This stylus is mounted on a thin leaf spring M0 and on a leaf spring or link I both being mounted on an arm of the housing I40 which is hollow and which encloses a magnetizing coil I40 supplied with direct cur rent from a suitable source. The housing and core I40 are iron and have an annular air gap in which is placed a small coil I40e. As this coil moves back and forth in the field thus produced, a pulsating current is generated therein which passes through wires I40 to an amplifier of any Well known type, the amplified current being used to operate a loud speaker. A permanent magnet may be used for this purpose, and the members I40 and I40 may be enclosed in the housing.

In passing from the motion picture projector to the sound pick-up device, the film M passes over a sprocket I I3 which is carried on a shaft lI4 (Fig. 22) which is driven by a gear H5 which meshes with an idler I I6, the latter meshing with a gear II! on the sleeve II8. This sleeve carries two arms II 9 which connect through suitable springs I with pins I2| on a plate I22 which is doweled to a shaft I23. This shaft carries a sprocket I24 around which the film M passes and which serves to draw the film steadily through the sound pick-up owing to the compensating and smoothing action of the springs I20. To further insure steadiness of the sprocket I24 the shaft I 23 is provided with a worm wheel I 25 which drives a governor I25 which is of the well known fiy-ball type used on phonographs to obtain a substantially uniform speed of the turntable. As the weights of the governor which are carried on steel members I21 fiy outwardly they force a plate I28 against a shoe I29 which tends to slow up the ac tion. By properly adjusting the distance of the shoe I29 from the rotating plate I28 a very smooth and uniform action of the governor is obtained. Where necessary, the sprocket I24 may be of the compensating type shown in Fig. 13.

In Fig. 21 is also shown a device for properly registering the picture and sound on a film. The projector and sound reproducer are secured to a table I30. For this purpose the projector may be held by screws I3I, and a suitable adapter as I32 may be used for holding certain types or kinds of bases on the table. In this way the distance-between the projector and reproducer may be maintained. In connection with this table I use a loop adjusting device comprising a roller I33 mounted on a lever arm I34 which is pivotally mounted at I35, and carries a pin I36 adapted to selectively engage holes I3! in the reproducer. Thus each hole may correspond to one type of projector. By setting the pin I36 in the correct hole and stretching the film over the roller I33, as shown in dotted lines, the correct spacing of the film between the projector and pick-up is obtained. After thus threading it through the projector, the roller I 33 is released to the fullline position leaving the loop I38 of the desired length.

While I have shown and described but a few embodiments of my invention, it is to be understood that it is capable of many modifications.

Changes, therefore, in the construction and arrangement may be made which do not depart from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1. Apparatus for recording sound on the edge of a motion picture film comprising a pair of rolls between which the film is passed, means for pressing the rolls together to firmly grip the film, means for supporting one edge of the film, and a vibratory recording tool adapted to engage the opposite edge of the film at the point where it is gripped, said opposite edge slightly overhanging the ends of the rolls.

2. Apparatus for recording sound on the edge of a motion picture film comprising a pair of rolls between which the film is passed, means for pressing the rolls together to firmly grip the film, means for supporting one edge of the film, a vibratory recording tool adapted to engage the opposite edge of the film at the point where it is gripped, said opposite edge slightly overhanging the ends of the rolls, and means in advance of the recording tool for trimming the edge of the film.

3. A sound recording device comprising a metal frame, an iron core extending inwardly from one end, the frame being spaced from the other end to form an annular air gap, a magnet coil about the core for energizing the same, a movable member in axial alignment with the core and mounted in the frame for endwise movement, said member having a disk mounted thereon, a rubber pad on each side of the disk to serve as dampers for the member, the core bearing against one of the pads and being adjustable endwise to vary the damping action, and a recording tool carried by the movable member.

4. Apparatus for recording sound on the edge of a motion picture film comprising a pair of rolls between which the film is passed, means for pressing the rolls together to firmly grip the film, means for supporting one edge of the film, and a vibratory recording tool having a chisel-like edge adapted to lie transversely of the edge of the film and adapted to engage the opposite edge of the film at the point where it is gripped, said opposite edge slightly overhanging the ends of the rolls.

5. Apparatus for recording sound on the edge of a motion picture film comprising a pair of rolls between which the film is passed, means for pressing the rolls together to firmly grip the film, means for supporting one edge of the film, and a vibratory recording tool having a chisel-like edge JOHN RIPLEY KIEL.

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