US1700833A - Sound-recording system - Google Patents

Description

Feh 5 1929.,

T. J. ENGEL SOUND RECORDING SYSTEM Filed Jan. 30, 1928 7 Patented Feb. 5, 1929.

UNITED STATES PATENT OFFICE- THEODORE J. ENGEL, OF BAYSIDE, NEW YORK, ASSIGNOR T BELL TELEPHONE LABO- RATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SOUND-RECORDING- SYSTEM.

Application filed January 30, 1928. Serial No. 250,411.

This invention relates to optical speech recording mechanisms and particularly to automatic film changing devices associated. with such recording mechanisms.

In recording acoustically modulated light waves onphotographically sensitive film it is desirable to record the light waves regardless of the duration of the speech or musical number without losing any of the record.

The time required to record the average speech or musical number is sometimes longer than the time required for the running of a film of standard length. This results in a loss of part of the record unless means are provided to instantaneously shift the recording operation to a new film.

An object of. the invention is to accurately transfer to photographically sensitive film a record corresponding to a series of successively occurring sound or picture variations.

A further object is to accurately record on several lengths of motion picture film a continuous record of successively occurring acoustically modulated light waves or picture variations withoutlosing any part of these records in transferring the recording operations from one length of film to another.

In accordance with the invention the above objects are accomplished by the use of an electric circuit comprising a plurality of re lays to control the operation of the motors which drive the film and to control the shutters of the recordng mechanism to admit or reject the light waves projected to the recording films. More specifically the invention employs two recording systems each comprising a film magazine with its associated lens, shutter, and a motor to drive the film. A single source of modulated light common to both systems is usedand consists of a light source, a light valve and spherical lenses to project the image of the light valve on to the recording films. The light is directed to each of the recording films by two silvered reflecting prisms which divide the light and reflect it to each of the films. An electric circuit comprising a plurality of relays interconnects the driving motors and the shutters. When the run of one standard length film is nearly completed a notch in the edge of the film engages a roller which closes circuits to operate the relays so as to close the driving motor circuit for thesecond film. When this motor attains the proper speed a notch in the edge of the second film engages another roller which closes an electric circuit to stop the motor of the first film and open the shutter of the second film. With a mechanism of this kind-there is no loss of time in transferring from one film to another which therefore gives a complete record of the picture variations and their accompanying musical number;

Fig. 1 is a diagrammatic view of the apparatus and circuit connections.

Fig. 2 is a detail of the filmand its associated tripper contacts.

Referring to Fig. 1, a light source 3 projects light rays to a spherical lens 4, then to light valve 5. Voice modulated currents from microphone circuit 20 are supplied to said light valve, thus varying the amount of light transmitted in accordance with the speech currents.

- A preferred form of light valve is disclosed in Patent 1,638,555, August 9, 1927, to E. C. Wente. These acoustically modulated light waves pass through lens 6 and are then divided and reflected, by silvered reflecting prisms 7, toward each of the sound recording cameras 1 and 2.

The two cameras being alike, it will simplify the description to consider only camera 2 for the present. This sound recording camera consists of casing 14. spherical lenses 9 and 12, film F film winding reels 15 and the film driving motor M Included in casing 14; are magnet 70 for controlling the shutter 11, and contacts R and R associated with the film for controlling the various switching operations.

Scenic cameras 26 and 27 record the action accompanying the speech or musical number and although necessary for a complete description they form no part of this invention.

The operation of the device is as follows:

Let it be assumed that both the sound recording mechanismsare at a standstill. If the operator wishes to start camera 2 he depresses key D which energizes relay 40 through contact 19 of relay 4:5, battery E of the key D is only momentary, a locking means is provided for relay 40, the circuit comprising armature 17 relay 40, armature 19, battery E and ground.

The shutters 11, 34, 10 and 35 are all connected in parallel circuit and each pair is so mechanically adjusted that when 11 and 34 are open 10 and 35 are shut and vice 'versa. Any switching operation affecting one set I will afiect the other set. The shutters operate on the well known principle of the ordinary camera shutter set on time exposure wherein two operations of the shutter lever are necessary to open and close the shutter.

The film F is now recording the acoustically modulated light waves. When film F nears the end of its run, an indentation in film by engaging tripper R, (equivalent to R shown in Fig. 2) closes contacts to energize relay 50 through battery E armature 23, relay 50 and ground. Armature 25 attracted by relay 5O closes the circuit to heavy duty relay 60, which attracts armature 28 closing the circuit to film driving motor M and power supply lines 30. The film F, has an indentation H about four feet from the starting end of the film adapted to receive tripper B, (Fig. 2). This tripper R falling into indentation H makes a double contact. Contact 29 closes the circuit to magnets 70, 75, 80, 85 through battery, windings of the magnets, contact 29, armature 18 and ground,

which opens shutters 10 and 35 and closes the shutters 11 and 34 of the first machine. Contact 31 closes circuit to relay 45 which attracts armature 19, thus breaking the looking circuit of rela 40. Armatures 16, 17 and 18 are release The release of armature 16 breaks the circuit of motor M thereby causing the film F to stop. The double contact controlled by R is so ad'usted that the contact 29 closes slightly efore contact 31 because contact 29 closes the circuit to the magnet through armature 18, to trip the shutters, and contact 31 closes the circuit to relay .45 which attracts armature 19 to break the locking circuit of relay 40, thereby releasing armae ture 18 from its contact. Therefore, it is necessary that the circuit through armature 18 be made before the second contact 31 opens the circuit.

It is obvious from the above description of the operation that either machine may be started first and the transfer from one machine to the other may be efiected without loss of any of the record, thereby eliminating the objections heretofore experienced in recording a musical or speech program on photographically sensitive film.

IVhat is claimed is:

1. In a recording system, a source of acoustically modulated light waves, a photographically sensitive film, a second photographically sensitive film, means for driving each of the films, means to project light waves from said source toward each of said films to produce a photographic sound record, and means controlled by said films to shut off said light waves from the first mentioned film and to Iproject said light waves upon said second 2. In a recording system, a source of acoustically modulated light waves, a photographically sensitive film, a second photographically sensitive film, driving means for each of said films, means to project light waves from said source toward each of said films to produce a photographic sound record, and automatic means controlled by said films for alternately starting and stopping each of said film drivmg means.

3. In a recording system, a source of acoustically modulated light waves, a photographically sensitive film, a second photographically sensitive film, driving means for each of said films, reflecting prisms for projecting light waves from said source toward each of said films to produce a photographic sound record, and film controlled electromagnetic 'means for starting one of said film driving light controlling means-with said driving' means.

5. In a recording system, a photographically sensitive film, a second photographically sensitive film, film controlled shutters associated with each of said films, a source of acoustically modulated light waves common to both of said films, means to project light waves from said source upon each of said films to produce a photographic sound record,

said light waves being admitted to either of said films under the control of said film con trolled shutters.

6. In a recording system, a photographically sensitive film, a second photographically sensitive film, a source of acoustically modulated light waves common to both of said films, separate driving means for each of said films, shutters associated with each of said films, said driving means and said shutters being simultaneously controlled by said films. a photographic sound record, shutters asso- 7. In a recording system, a source of acousciated with said films and means controlled tically modulated light waves, a photographiby said film to alternately open and close each 1 cally sensitive film, a second photographically of said shutters.

5 sensitive film, driving means for each of said In witness whereof, I hereunto subscribe films, means to project light waves from said my name this 28th day of January, 1928; source toward each of said films to produce THEODORE J. ENGEL.

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