US2235513A

US2235513A - Sound recording system

Info

Publication number: US2235513A
Application number: US288613A
Authority: US
Inventors: Arthur C Blaney
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1939-08-05
Filing date: 1939-08-05
Publication date: 1941-03-18
Anticipated expiration: 1958-03-18

Description

March 18, 1941. A. c. BLANEY 2,235,513

SOUND RECORDING SYSTEM Filed Aug. 5, 1939 7 Sla/VAL Sol/ece Afan/ue C. JLANEY? www Patented Mar. 1,8, 1941 UNITED STATES SOUND RECORDING SYSTEM Arthur C. Blaney, Los Angeles, Calif., assignor to Radio Corporation of America, a corporation of Delaware Application August 5., 1939, Serial No. 288,613

14 Claims.

This .invention relates to sound recording systems :and particularly to the recording of sound -on motion picture film.

It is the gener-al practice in motion picture studios to record sound in related and unrelated sequences which are spliced .together at the end of the day and processed. The 'picture sequences `are also photographed and treated in the same manner. The sound and picture negatives are -then printed individually .but reproduced in synchronism for inspection the neX-t day. Certain sequences or sections of sequences are marked for `deletion at this inspection, while subsequent editing eliminates land interchanges other picture 15 and sound sequences to form the story continuity. For this purpose one or more sound prints from the original negative may be made and used.

When the nal cutting or editing has been completed, the original negative is then cut to con- .20 form with the fin-al edited print, from which original negative anew print is made for -rerecording purposes. The rerecording step produces the nal negative from which the combination picture and sound print is made for release to the 525 theatres. An individual sound print may, sometimes, however, be used in -theatres for preview showings. It is realized from the above that several printings and several processings are required before the nal print is produced, each l :30 step providing the opportunity for, and generally, introducing some distortion and noise.

Sound motion picture studios are, however, aware of a type of sound recording system known as the reverse negative or direct positive sys- 35 tem, such as disclosed and claimed in copending iapplication Serial No. 168,173, led October 9, 1937. This system produces a positive record by the original recording and one which is suitable for reproduction, thus eliminating the necessity Ll0 of a printing step and a print. Although this system has many advantages, such as being a much quieter sound track from the ground n-oise standpoint, it is general practice to make a negative therefrom in order .to obtain additional prints 45 for editing and inspection purposes. However,

the direct positive system does provide an immediate record after one processing step which may be used for the rst daily inspection and is particularly good for rerecording purposes. 50 The present invention is directed to a recording system which provides on .the same iilm both a direct positive record which may be immediately reproduced and also -a negative record of the same sounds on the same film strip, identical 55 portions of the sounds'belng opposite one an- This double track recording system is now used Y as follows: Although the direct positive track may be reproduced for inspection and sometimes is, prints are made from the negative track only, these prints being used for inspection and editing. The double track nlm is then cut according to an edited print, which automatically cuts both lthe negative and direct positive tracks. NOW instead of havin-g I to make another print from the negative for rerecording purposes, the cut direct positive may be employed for rerecording, this track being not only superior by being more quiet than a print made from the negative, but it saves the time and cost of making a rerecording print. It also sometimes occurs that a preview is given wherein the picture is projected from one lm and the sound is reproduced from a separate sound nlm. The quiet direct positive Amay be used for this purpose.

Also, certain types of sound tracks, such as push-pull tracks requiring special reproducing apparatus not in general use in theatres, have been foundadvantageous for the original recording in the studios where such special reproducers are available. Thus, this type of sound track is used for the direct positive for use in the studio, while the adjoining negative track may be of the standard form for universal use, although it may also be of the push-pull type for studio use.

The principal object of the invention, therefore, is to facilitate sound recording in the production of motion pictures.

Another object of the invention is to simultaneously record one type of sound track adjacent 'and opposite a second type of sound Itrack on the Aportion of the lm.

Although the novel features which are believed to be characteristic of this invention are pointed out with particularity in the claims appended herewith, the manner of its organization and the mode of its operation Will be better understood by referring to the following description read in conjunction with the accompanying drawing forming a pant thereof in which- Figure i is a diagrammatic View of a recording system embodying the invention; land Figure 2 is a lm representing the type of sound tracks produced with the system of Fig. 1.

Referring now to Fig. 1, a pair of light sources represented by filaments 5 and 6 produce light which is collected by respective condenser lenses 8 and 9 for projection through respective masks i il and II.. The light through the mask I0 passes a pair of noise reduction shutters I3 under control of a solenoid i4 connected in the standard manner to a noise reduction unit as disclosed and claimed in U. S. Patents 2,102,776; 2,102,777; and 2,102,773. The light passing the mask I0 is projected on a galvanometer mirror IB having an actuating coil il connected to a signal source as shown in the above-mentioned patents.

The light passing the mask I0 and shutters I3 and striking the mirror I'I is projected on a slit mask 20 having a slit 2l therein, the light beam at times of no signal being shown by shaded area 22 on the mask 20. The light passing the slit 2I is projected on sound track area 26 of a Iilm 24 by projection lenses 25.

The light passing through mask II is also projected upon the galvanorneter mirror I6 and then reflected to a slit mask 2 having a slit 28 therein, the light beam at times of no signal being represented by the shaded areas 30. The light passing the slit 28 is projected on sound track area 32 of the film 2li by projection lenses 3|.

The type of aperture in mask I0, noise reduction shutters i3, and the Vibration of mirror I6 produce a standard duplex bilateral variable area sound track, while the mask I I with its

solid portions

34 and 35 and the Vibration of mirror I6 produce a push-pull class-B sound track of the direct positive type, as disclosed and claimed in the above-mentioned copending application. Referring to Fig. 2, the standard duplex track is shown along the left-hand side of the iilm and comprises opaque Zero signal lines 31, a single frequency modulation 38 for purposes of illustration, and bias shutter traces 39, the darkened areas being the opaque portions of the film and the other portions being transparent. This is a negative track and, in printing, the opaque and transparent areas are reversed to produce the normal positive antiground noise sound record. On the right-hand side of the film 24, the modulated areas 4I and zero lines 42 are transparent and the remaining areas 43 are opaque, thus representing a positive sound track record of the class-B type.

The sound track 32 is immediately reproducible, while the negative 26 must be printed to produce the usual type of commercial print. The track 32 is also quieter than a printed track made from the negative 2S and thus is superior for reproduction and rerecording purposes. It requires, of course, a reproducer with the pushpull type of reproducing elements and circuit, but this equipment is available in motion picture studios. The prints made from the track 26, on the other hand, are reproducible in all standard equipment and may be used universally. This method of recording, therefore, provides a higher quality iinal print since it eliminates a printing step and a processing step and utilizes a Ypreferred form of original recording for rerecording. It correspondingly reduces time and expense.

It is to be understood that the forms of the simultaneously made tracks may be varied or changed without departing from the spirit of the invention. For instance, both tracks may be of the push-pull type since both are reproduced for inspection or rerecording purposes on studio equipment, the rerecorded negative, however, being of the present standard type for release.

I claim as my invention:

1. The method of sound recording comprising simultaneously recording a negative record and a direct positive record on the same iilm of the same sound Waves.

2. The method sound recording in accordance with claim 1 in which said negative record has a type of sound track different from that of said direct positive.

3. The method of sound recording comprising simultaneously making a, direct positive record and a negative record of sound waves, printing editing prints from said negative record, and rerecording from said direct positive record to produce a iinal release print negative.

4. The method of sound recording comprising simultaneously making a negative record and a direct positive record of sound waves, printing editing prints from lsaid negative, rerecording said direct positiverecord to a second negative record, and printing release prints from said second negative record.

5. A sound film comprising a negative sound record and a direct positive sound record of the same sound waves on the same nlm.

6. A sound film in accordance with claim 5 in which said negative record has a track of a type diierent from that of said direct positive.

7. A sound film in accordance with claim 5 in which the same sounds in each record are oppositely disposed transversely of said film.

8. A sound nlm in accordance with claim 5 in which one of said records is a standard type of sound track and the other of said records is a push-pull type of track.

9. The method of sound recording comprising simultaneously making a direct positive record and a negative record of sound Waves, making a print from said negative record, editing said print, cutting said negative record and said direct positive record to conform to said edited print, and rerecording said direct positive record to a second negative record.

10. The method of sound recording in accordance with claim 9 in which said second negative record is printed to make release prints.

11. A sound recording system comprising means for recording sound Waves as a negative sound record upon a iilrn, and means for simultaneously recording said sound waves as a direct positive sound record on said same lrn oppositely disposed from said first record transversely of said lm.

12. A sound recording system comprising means for recording sound waves as a negative sound record, and means for simultaneously recording said sound waves as a direct positive sound record, both of Said means including a. common element for recording on the same iilm, said element being a light beam modulator upon which said sound waves are impressed.

13. A sound recording system comprising a plurality of light sources, a pluralityof respective `optical units for projecting light from lsaid light sources to anim, a plurality of respective masksl for determining the type of sound track to be recorded by each of said units, and a light beam modulator common to said light sources, optical units and masks for simultaneously recording sound waves impressed on said modulator, one respective light source, optical unit and mask producing a negative sound record, and another respective light source, optical unit and mask producing a direct positive sound record.

14. A sound recording system for recording the same sound waves in a plurality of sound record tracks upon the same nlm, comprising a plurality of individual recording units for producing said tracks on said lm, one of said units producing a negative sound record 'and another of said units producing a direct positive sound record, and a light modulator common to all of said recording units and upon which said sound waves are impressed as electrical currents substantially corresponding in frequency and amplitude to said sound waves.

ARTHUR C. BLANEY.