US2485839A

US2485839A - Magnetic-photographic rerecording system

Info

Publication number: US2485839A
Application number: US23897A
Authority: US
Inventors: Dorothy L O'dea
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1948-04-29
Filing date: 1948-04-29
Publication date: 1949-10-25
Anticipated expiration: 1966-10-25

Description

Oct. 25, 1949. D. l.. ODEA 2,485,839

MAGNET I C-PHOTOGRAPHI C RERECORDING SYS TEM Filed April 29, 1948 Dafa rffy @bf/4.

1N V EN TOR.

iatented Oct. 25, 1949 MAGNETIC-PHOTOGRAPHIE RERECORDING SYSTEM ADorothy L. ODea, Los Angeles, llalii., assignor to Radio Corporation oi America, a corporation o! Delaware Application April 29, 1943, Serial No. 23,897

7 Claims. l This invention relates to sound recording and reproduction, and relates particularly to a record (SDL transfer method and system whereby a magnetic type of record may be rerecorded to a photographic type of record.

and directors desire an immediata check on lthe record made before passing on to the next scene or before the set is dismantled. However, before the sound track may be released, it must be rerecorded to a photographic sound record so as to be combined with the picture and reproduced in theaters which are equipped with photographic sound reproducing apparatus.

The present invention is directed to a rerecording method and system for transferring a magnetic record a separate photographic nlm, or, if desired, to the same nlm carrying the magnetic record, lout on which a photographic emulsion is also present. The principle of light rotation by stresses in dense glass is utilized in making the transfer. That is, the magnetic record varies the magnetic neld in a thin glass plate through which the recording light beam is passed. The stresses in the plate modulate the light which is then projected to a separate photographic nlm or to a photographic emulsion on the magnetic nlm.

The principal object of the invention, therefore, is to facilitate the transfer of a magnetic record from a magnetic record carrier to a photographic record carrier.

Another object of the invention is to provide an improved method of and system for rerecording a sound record from a magnetic tape nlm to a photographic nlm.

A further object of the invention is to provide an improved rerecording system between magnetic and. photographic record mediums.

Although the novel features which are believed v to be characteristic of this invention will be pointed out with particularity in the appended claims, the manner of its organization and the mode of its operation will be better understood by referring to the following description read in itt-400.3)

conjunction with the accompanying drawings, forming a part hereof, in which:

Fig. l is a diagrammatic, perspective drawing of a rerecording system embodying the invention, and

Fig. 2 is a cross-sectional view of the light modulator taken along the line 2-2 of Fig. 1.

Referring now to the drawings, a magnetic tape or nlm 5 is pulled between a shoe 6 and a laminated, circular core 8 by a sprocket 9 having a pad roller I0 thereon. Although the magnetic tape is shown as one having a single row of perforations or sprocket holes I2, and the sprocket 9 has teeth at one end tl. neof, it is to be understood that the magnetic record carrier may be on a tape or nlm having a double row of sprocket holes, or may be on a tape without perforations which is then driven by a capstan.

The core 8 has a small gap provided by insulation Il and a larger gap diametrically opposite in which is a dense glass sheet I5 of approximately one-half a mil thick. The core 8 has openings Il and I8 on each side of the plate I5 so that light may be passed through the plate i5, as showninFig. 2.

The optical system for recording a record on a photographic nlm 2li includes a constant intensity light source 2l, a condenser lens 22, a polarizing sheet 24, a second polarizing sheet 25, a lens 26, a slit mask 21, and a projection lens 28. The nlm 20 may be a thirty-nve millimeter strip with a double row of perforations, or may be sixteen millimeter with a single row of perforations. With no magnetic tape passing the gap i4, the two polarizing sheets 24 and 25 are arranged so that no light, or a very small amount of light, will pass to the nlm 20. However, if any rotation of the light beam occurs by stresses in the plate I5, light will pass the plate 25 to the nlm 20 in an amount depending upon the degree of stress in the plate I5.

Thus, to transfer a magnetic record on the tape 5 to a photographic record on the nlm 20, the tape 5 is advanced past the gap Il, causing various degrees of strain in the plate I5 which will vary the quantity of light reaching the nlm 20, and a variable density type of record corresponding to the magnetic record will be recorded on nlm 20. If the tape 5 also carries a photographic emulsion, it could be directed to the position of nlm 20 and have a photographic record recorded thereon.` The glass plate I5 may also be positioned at the gap Il with the neces-l sary light passing openings in the core 8, as shown at l1 and I8. The glass plate l5 is preferably dense nint having a high index of refraction, while the tape or nlm l may be' advanced across the gap Il with a reversed curvature to that shown, thus eliminating the shoe l.

I claim:

1. A sound record transfer system comprising a medium carrying a magnetic sound record. a photographic emulsion adapted to have a sound record recorded thereon, a magnetic core having a pair of gaps therein and in which the magnetism is varied by said magnetic record passing one of said gaps in said core, an optical system for directing light to said photographic emulsion, a pair of crossed light polarizing elements in said optical system, and a light rotating element in said other gap of said core for modulating the light in accordance with the degree of magnetism in said core produced by said magnetic record.

2. A sound record transfer system in accordance with claim l, in which said light rotating element is a dense glass plate said light passing through openings in said core and said glass.

3. A rerecording system for transferring a magnetic record to a photographic lm comprising a magnetic core having a pair of diametrically positioned gaps therein, a thin glass plate located in one of said gaps in said core, means for impressing a light beam of constant intensity on said glass through an opening in said core, means for advancing a magnetic record past said other gap in said core for varying the magnetism therein and in said glass, thereby modulating the light emerging from said glass, and an optical system for projecting said modulated light to said lm.

4. A rerecording system in accordance with claim 3, in which said light passing means and said light projecting means include a light source of constant intensity, a polarizing element between said source and said core. and a second Iolarizing element between said core 'and said 5. A rerecording system in accordance with claim 3, in which said thin glass plate is of dense fiint glass having a high refractive index.

6. A rerecording system for making a photographic record from a magnetic record comprising a core having a pair of gaps therein and adapted to be magnetized, means for passing a magnetic record past one of said gaps for magnetizing said core in accordance with the magnetic variations of said record, and a photographic sound recording unit including a light modulator in said other gap of said core. the variations in magnetism of said core actuating said modulator.

7. A rerecording system in accordance with claim 6, in which said light modulator is a dense ilint glass having a high refractive index and said core has openings therein on each side of said glass through which the recording light passes.

DOROTHY L. ODEA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,961,706 Pajes June 5, 1934 2,039,742 Schinzel May 5, 1936 2,165,307 Skellett July 11, 1939