US2330331A - Control track recording and synchronizing system - Google Patents

Description

Sept. 28, 1943,

CONTROL TRAGK RECORDING AND SYNCHRONIZ ING SYSTEM Filed Jan. 29, 1941 A. c. BLANEY v 2,330,331 A INVENTOR: 1 A2 Hue FLA/V5);

BY W f (ATTORNEYS.

Patented Sept. 28, 1943 CONTROL TRACK RECORDING AND ,SYNCHRONIZING SYSTEM Arthur C. Blaney, Los Angeles, Calif., assignor to Radio Corporation of America, a corporation of Delaware Application January 29, 1941, Serial No. 376,521

9 Claims.

This invention relates to sound recording and reproducing systems and particularly to a system for producing a control record for a signal record and for marking or synchronizing the two records for subsequent combination.

It is well known in the art that the level of a film sound record, may be controlled during reproduction by another photographic record separate from the signal record or by a record contained on the same film strip. Such a type of signal and control film record combination is disclosed in copending application Serial No.

181,634, filed December 24, 1937, wherein the control record is interposed between the sprocket hole perforations, these perforations being used to produce a 96-cycle carrier frequency for controlling the amplification of the signal record.

The present invention is directed to a system for producing a control record of a certain signal record after the signal record has been made. That is, after a signalrecord of sound efiects or background noises has been recorded (it is also applicable to a sound record of'dialogue or a combination record of dialogue and background effects), the signal record is reproduced with or without the picture with which it is associated. During the reproduction of the sound record, the level of reproduced sound is varied toenhance the dramatic effects thereof in relation with the associated picture. After one or more rehearsals to obtain the desired series of variations in level and the points of variation, a control record of the variations is recorded, which will be subsequently combined with the signal record on the final composite picture and sound print. Since the control record must be properly timed and thus properly aligned with the signal record, some method and means for obtaining synchronization are required.

In the sound recording art, it is well known how synchronization marks may be applied by the use of clapper-sticks to picture and'sound negatives during recording. Also, the use of simultaneously energized fogging lights for the picture and sound negatives is well known.

. However, in the present problem, no picture negative is involved, while one of the films is a sound ently' 'of the recording of the control record. Also, the record being made is unusual sinceit is a record 01 manual variations which are recorded in the areas intermediate the sprocket holes.

The principal object of theinvention, therefore, ls to facilitate the production or a. control record being reproduced substantially independrecord and the subsequent combining thereof with a signal record. a

Another object of the invention is to produce synchronization marks on a signal record and its control record.

A further object of the invention is to improve the marking of a control record for the subsequent combination thereof with a signal record for which the control record is madej Although the novel features which are believed to be characteristic of this invention are pointed out with particularity in the appended claims,

the manner of its organization and the mode ofv its operation will be better understood by re,-

ferring to the following description read in conjunction with the accompanying drawing forming a part thereof in which Fig. 1 is a diagrammatic drawing embodying the invention;

for which a. control record is made; and

Fig. 3 is a fragmentary view of a control record made for the signal record of Fig. 2.

Referring now to Fig. 1, a film 5 carries a signal record 6 for which a control record is to be made. The signal record may be reproduced in any well known type of manner employing a lamp 8, lenses 9 and I0, and a photoelectric cell ll. The output of photo-electric cell II is impressed upon an amplifier l2 and then fed to a. variable gain amplifier l4 and a recording amplifier l3, the latter feeding a-loudspeaker 40 and the variable gain amplifier feeding a loudspeaker l5. For controlling the gain of the variable gain amplifier I4 and consequently the amplitude of the signal being reproduced in loudspeaker I 5. an oscillator IB of any suitable frequency, such as 500 cycles, is connected through a potentiometer 2i and a'rectifier 25 to the variable gain amplifier 14. The output of potentiometer 2| is also impressed upon a rectifier 29 to produce the control record, as will be explained hereinafter.

The optical portion of the recording system for the control track is shown diagrammatically as including a lamp H, a collecting lens l8, a mask IS with an aperture 20 therein, and a. lens 22 for projecting the light passing the aperture' by a lens 8|: :The form oi the light beam promixer operator.

jected on the mask 26 is shown by the dotted lines 33. v y

The galvanometer 24 has two windings 35 and 36. The winding 35 is connected to the output of recording amplifier I3 when a switch 38 is closed, while the winding 36 is permanently connected to the output of rectifier unit 29. The winding 35 of the alvanometer is adapted to cause the mirror 23 to follow the instantaneous values of the signal modulations, while the winding 36 causes the mirror to follow the rectifier output of the oscillator I6 as varied by the potentiometer 2|. Although the light modulator is shown as a two-winding galvanometer, it is to be understood that noise reduction shutters as disclosed in U. S. Patent No. 2,102,777 of December 21, 1937, may also be used as the control track modulator. Thus, with the switch 38 closed, the light beam 33 will be vibrated in accordance with the instantaneous values of the signal, while with the switch 38 open, the light beam is moved only in accordance with the variations in the potentiometer 29.

Thus, to produce a control track which is to subsequently control the reproduced level of the signal track independently of the actual level of the signal track, the film is reproduced through units II, I2, I3, I4, I5 and 40. The variations in light caused by the beam 33 being vibrated across the slit 21 due to manipulation of the potentiometer 2I are then impressed upon the sprocket hole area of the film 30. With the switch 38 closed, any signal being reproduced will be impressed on the winding 35 and such signal will be recorded, the opening of the switch discontinuing such recording. During reproducing of the signal, variations in the normal amplitude level thereof may be varied by the potentiometer 2| to enhance the dramatic effects of the sound. This is accomplished by varying the output of the oscillator I5 as impressed on rectifier 25, which controls the gain of variable gain amplifier I4. However, since the output of potentiometer 2I is divided and fed to rectifier 29 connected to winding 36, the light beam 33 will be varied in ac-' cordance with the potentiometer or signal variations. film is to be combined with the signaltrack on film 5, it is necessary that synchronizing marks be correspondingly located on the film 5 and film 30. This is accomplished as follows:

Referring now to Fig. 2, in which the signal track film 5 is shown, it will be observed that there is spliced to the upper portion of the film 5, a constant frequency modulation tone track 5 of 1000 cycles, a frequency of this approximate value having been found to be particularly desirable from both the audible and visual standpoints. Its audibility is desired because the switch 38 is actuated by an operator in accordance with what he hears in the speaker 40, and it should be readily visible in order to be detected by the film editors. Thus, such a section of 1000-cyc1e modulation track is spliced at point 45 to the signal film.. At the start of recording, the switch 38 is closed and the IOOO-cycle frequency is reproduced in the speaker 40 and simultaneously impressed upon the winding of the galvanometer 24. As soon as the l000-cycle tone disappears, the operator opens the switch 38, and'the control track is then recorded in accordance with the variations of potentiometer 2| made by a Although the tone is also reproduced in loudspeaker I5, this speaker is located in. a projection room while the recorder is Since the control track so recorded onat a distant point and the speaker 40 is required for the recording operator.

The result of this operation produces a control track, the section thereof corresponding to Fig. 2 being shown in Fig. 3. It will be noted that the 1000-cycle tone record is recorded similarly to and in the form of the lOOO-cycle tone record shown in Fig. 2, while the control track itself is shown during a no-variation period as of constant width. To illustrate that the signal modulations shown at 44 in Fig. 2 are to be reproduced at a higher than normal level, it will be noted that the control track has gradually narrowed down as shown at 45 in Fig, 3, which, in the final reproduction, will increase the gain of the signal reproducing amplifier in a manner similar to the variations in gain of the variable gain amplifier I4 by the varied output of the rectifier 25.

Since the present invention is directed to the production of a control film record for a signal film record and the synchronizing of the two film records, it will be noted that these film records are identically marked in a manner to facilitate their particularly accurate combination by the film editors. The two sound films may be first combined into a print having only the signal and control tracks thereon, or they may be simultaneously printed to the final combination sound and picture print. In either case, the proper relative position of the two tracks may be readily adjusted.

I claim as my invention:

1. A synchronizing method for marking a control record film being recorded with a signal film being reproduced comprising audibly reproducing a tone and the signal from said signal film in serial order, recording only said tone on said control record during the reproduction thereof, the recording of said tone being discontinued after a predetermined period while continuing the reproduction of said film being reproduced, and recording on said control record the variations in amplitude of said signal record.

2. A system for providing synchronizing marks for a pair of films, one film being recorded simul taneously with the reproduction of said other film comprising means for reproducing a tone and a signal from said film being reproduced, said tone being reproduced at a different time from that of said signal, means for recording said tone on said film being recorded during the time when said tone is being reproduced, and means for recording the variations in amplitude of said signal on said film being recorded during the time said signal is being reproduced,

3. A system for providing synchronizing marks on a pair of films, the records thereon to be combined on a single film comprising means for obtaining a tone record on one of said films, means for reproducing said tone record, means for recording said tone record on said second film, and

means for discontinuing the recording of said first film to said second film while continuing the reproduction of said first film.

4. A system for producing a control record film for a signal record film with synchronizing marks thereon comprising means for obtaining a tonerecord on said signal record film, means for reproducing said tone and signal record, means for recording only said tone record on said film; and means for recording the variations made in the normal amplitude of said signal recorg during the reproduction of said signal recor 5. The method of producing a control record film for a signal record film with synchronizing marks thereon comprising attaching a tone rec- 0rd to said signal record film, reproducing said tone and signal record in a serial order, recording only said tone record on said control record film, and recording thereafter on said control record film the variations made in the normal amplitudes of said signal record during the reproduction thereof. 1

6. A system for the production of a control record film for, an existing signal record film comprising means for obtaining a tone record in advance of said signal record on said signal record film, means for translating said tone and signal record into electrical currents, means for translating said currents into sound waves, means for recording only said tone currents, means for varying the amplitude of said signal currents, and means for recording a record of the variations made in the normal amplitude of said signal currents during the translation thereof into sound currents.

7. A system in accordance with claim 6 in which said means for varying the amplitude of said signal currents includes an oscillator, arectifier for said oscillator, a variable gain amplifier for said signal currents connected to saidrecti fier, and means for varying the output of said oscillator as impressed on said' variable gain amplifier to vary the amplification of said signal currents.

8. A system for the production of a control record film for a signal record film comprising means for translating said signal record film into electrical currents, said signalrecord containing therein a tone record, means for translating said electrical currents'into sound waves, means for recording only that portion of said signal record film containing said tone record, means for vary,- ing the amplitude of said signal current during reproduction, said means including avariable gain amplifier, and means for recording said variations in gainas said control record.

9. A system in accordance with claim 8 in which said amplifier varying means includes an durlng the reproduction of said signal

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