US2384131A - Sound recording and reproducing system - Google Patents

Description

Sept. 4, 1945. c. L. PRICE I 2,384,131

SOUND RECORDING AND REPRODUCING SYSTEM Filed Jan. 10, 1944 2 Sheets-Sheet 1 19 lforn e5.

Sept. 4, 1945. c. PRICE 2,384,131

SOUND RECORDING AND REPRODUCING SYSTEM I Filed Jan. 10, 1944 2 Sheets-Sheet 2 V l 75/ 7 II lmrmmuuumuluummmnwuumuuumnu v ll/11111111 null/1m.n n 1 nu mnmmmu I Patented Sept. 4,1945

cummi L. Price, Oakland, Calif. I Application January 10, 1944, Serial No. 517,782

6 Claims. (Cl.,l79. '0.3)

This invention, a sound recording and reproducing system, is an improvement over existent systems such as the molded plastic and soundon-film types, in that the highest degree of fidelity is attainable with an absolute minimum in size, volume and weight 'of the recordings.

With the conventional sound-on-fllm method of recording and reproducing sound, about 60 or more feet'of 35 mm. film, and corresponding lengths of 16 mm. and 8 mm. film is required to record and reproduce each minute of program.

The decreased lengths with 16 mm. and 8 mm.

film are not due to any desire or anticipation of reducing the length of the recording or sound track, but develops through amatter of necessity, the desire being merely to reduce thesize of the frames which in turn requires thatthe portion of the sound track included in a 35 mm. frame must be reduced along with the picture to fit in the smaller frame. With my invention a one-minute program of equal fidelity is reproduced from only 2% feet of film, and twenty-five or more recordings or different sound tracks can be recorded on an 8 mm. film.

Plastic records are bulky-and heavy, very easily damaged, and deterioratefairly rapidly with repeated playing, while with my type of record-' ing, extremely light weight, minimum bulkiness, and freedom from damage and deterioration are prevalent. a

With my invention, spiral recordings can be made on 35 mm. film to play for the same length of time as standard disc records. If desired, these spiral records can be produced in spaced relation on a continuous strip of 35 mm. film and thus used with suitable selecting mechanism in the reproducing unit, or the recordings'may be separated into individual records.

The recordings are preferably reproduced from the original recording or matrix, to a scale conforming to the resolving power of the film to be used, and then preferably projected to a size about equal to that of the original record, with the enlarged image of the sound track in lightand shadow interceptedby a suitable photo-cell, followed by suitable amplification and translation into sound.

The objects and advantages of the invention are as follows:

First, to provide a system of sound reproduction in which the greatest degree of fidelity it attainable'.

Second, to provide a system in which the recordings are of minimum size and weight.

Third, to provide a system in which the recordings are photographically formed from a matrix having a normal'size sound track, on a relatively small area or length of film, to -a greatly reduced scale. a

Fourth, to provide a system in which an original sound track ormatrix ismadeby conventional sound-on-film recording apparatus, and recordings made therefrom to a greatly reduced scale.

Fifth, to provide a system in which the recordings are produced from' a normal sound track. by photo-copying to a greatly reduced scale, on a transparent base photographic emulsion followed by suitable development. 1

Sixth, to provide a system in which .soundis normally convertedlnto photographic densities to form a sound track of normal size, and producing recordings for use by photographingsaid sound record or track to a scale established by the resolving power of the emulsion used.

Seventh, toreproduce sound from said recordings of greatly reduced scale. by projecting a traveling image of the sound track through an optical system to a size approximating thatof the original sound track, photometrically intercepting the enlarged light and shadow image, amplifying the effects of the intercepted light and shadow fluctuations, and' translating the amplified fiuctuations into sound waves.

Eighth, to provide a sound reproducing system the photo-sensitive means, and translating the amplified fluctuations into sound waves.

Other objects and advantages of the invention will become apparent as the following description is read on the accompanying drawings, in which: Fig. 1 is a fragmentary plan view of a matrix with a spiral sound track formed thereon through conventional sound-on-film recording means. r

Fig. 2 is a full size plan view of one of the recordings as made from ,a spiral matrix,.on 35 mm. film, with the sound track only illustrativelv indicated on a greatly enlarged scale.-

Fig. 3 is a side elevation of the reproducing unit for the spiral form of soundtrack; and is partly shown in section. i

Fig. 4 is a front elevation of Fig. 3.

Fig. 5 is a plan view of the recording holder I j of copying ribbon matrices to a reduced accordance with this invention.

Fig; 6 is a seetiontaken on line 8-6 of Fig. 5. Fig. 7 isa modification of the matrix fragmentarlly shown, and indicating a multiplicity of sound tracks in parallel.

Fig. 8 illustrates a modification of the feeding 1 means, for feeding lineal or ribbon recordings, and includes means for adjusting the record ing transversely for selection of the respective sound tracks for different programs, and is taken on a line' 04 of Fig. 9.

Fig'. '9 is a front elevation of the reproducing unit for ribbon type recordings. V

Fig. 10 is a side elevation of Fi 9.

Fig. 11 is a fragmentary view of an 8 mm. ribbon type recording, with a plurality of sound tracks in'parallel. a

Fig. 12 diagrammatically illustrates the-method scale in f The matrix Fig. l, is preferably formed on a circular disc ofmoisture proof base supported mission;

photographic emulsion, and may be either, developing paper, plate, or film; plate or film being preferable because paper would necessitate copying to the reduced size by reflection, while a 1 plate or film is correctly copied through trans- During the recording process, which is car- 1 riedout by conventional sound-on-film recording equipment, the film, instead of being fed Zineally, is fed, spirally through simultaneous 1 rotation and diametric adjustment, so that the i sound track It will be formed as a continuous spiral from the periphery ll toward the axis l2,

; with a clear space llleft between convolutions. Processing is carried out byany of the conventional processes, thecircular form permitting rotational agitation in the processing solutions,

thereby avoiding edge wash as would occur with rectangular sheets, assuring uniformityin proc essing even with variable density types of sound tracks.

The correctly processed matrix is copied through conventional methods, such as a reducingcamera, .on a small section or short length of film having very high resolving power, such of about.24 mm., (the space ll between the 1 as'Micro-file or Graticular film, with a two-foot diameter matrix readily reduceable to a diametersprocketholes II in 35 mm. film), as shown in Fig. 1

2 though other sizes of film can be used, and the recording made larger or smaller,-as may be desired or required. There is one distinct ad- 1 vantagein having the recording as small as possible; it obviates the necessity for a compara-j tively. long focus lens, or for a transverse feed} for a short focus lens, for, the reproducing system.

In making these miniature recordings, the film applied to the clear ends or sides, with the title or number simultaneously indicating by its cor- 1 rect reading position the correct placement of the recording in the reproducing unit. Such equip ment .and devices are well known in the art and are therefore believed to require no description.

In connection with the production of these miniature or microscopic recordings, it might be mentioned that Micro-file film is capableof resolving about 230 lines per mm., while Graticular film is capable of resolving about 500 lines per mm. The resolving powers of these films are therefore respectively about i and 2a. Thus, if the matrix is 24 inches in diameter with the pitch P of the spirals equal to /6 inch, the pitch p of the spirals on a 35 mm. reduced recording will be about .005 inch or 127a, with the sound track having a transverse width of about .0025

inch or 63 and the space between the spirals also,.0025 inch or 6311.. This is equal to about sixteen: times the resolving 'power'of- Micro-file film, and thirty-two times that of Graticular film, a very ample margin. a

With conventional recording and reproducing methods, each minute of program requires at least feet of 35 mm. film, and corresponding lengths of 16 mm. and 8 mm. film, though, as previously stated, this reduction is made to 16 or 8 mm. film only as a matter of necessity, to condense the relative proportion of sound track within the space occupied by one frame or picture. With my system only 2 /2 feet of Graticular film, or 5 feet of Micro-film, is required for a recording of similar frequency and fidelity, and it is easily possible to record twenty-fiv sound tracks in parallel on a strip of 8 mm. film, with only 37 feet being required for fifteen-minute recordings. The matrix can be'made on a comparatively wide ribbon, three or four inches, if a large number of sound tracks'are to be produced on the same miniature recording. However,from one to eight sound tracks canbe recorded on '35 mm, film, ard several-of these can be recorded to the reduced scale on a single strip of 8 mm. film. Obviously, this system is not limited to 8mm. film. Any desired size can be used. .The reproducing unit forthe spiraltype of recording is illustrated in its simplest form as comprising .an enlarging unit together with suitable feeding means, which broad statement applies equally. to the lineal or ribbon type of recording.

A projection lamp i8 is housed in a suitable lamp housing I 9 which at its lower end has a very narrow slit 20 of sufilcient length to extend over the cumulative recorded width of the series of parallel recording, or for spiral recordings,

across the radial width of the spirals which would be somewhat less than the radius of the recording for spiral'sound tracks, and which in the case of 35 mm. recordings 2! would be about 1 cm., as

there would be no sound track close .to the axis.

It is understood that a suitable condenser system.

or diffusion screen, or both, may be incorporated in the illuminating unit. a

The holder and turntable for the spiral type of recording consists of a gear 22 having an axial passage 23 equal in diameter to the diameter of the recording, and has combined locators and spring clips 24 with the locating shouldersspace'd apart a distance exactly equal to the widtheof the recording blank. An indexing'button 28 is receivable'in the hole I 6 for accurately locating the recording lengthwise; the recording being slipped underthe clips and pushed forward until the hole. snaps over the button/261v Projecting from the underside of this gear is a bearing collar 21 which rotatably fits in a gib bearing 28 which is'integral with the arm 29 which extends from the shaft bearing v30 which is mounted on the upright 31. This bearing 28 has a lens barrel 32 located eccentrically and in registry with the light beam slit 20, and hasa suitable lens combination 33 mounted in the lens 2,384,131 barrel. The projection lamp housing is mounted in a head 34 which. is hinged at 35 so that it can conveniently be tilted out of the way to provide access to'the recording holder.

Mounted in bearings 16 on the base 31 is a feed screw 30, and in parallel relation to the feed screw is a guide rod 30 on which is slidably mount ed one end of a support which has a half nut 4| formed at its other end to threadedly cooperate with the screw 38, and a handle '42 projects beyond the half nut for manual lifting of the half nut out of engagement with the screw 18 so that the support can be slidably returned to its starting position.

Mounted on the support "is a photo-cell unit 43 which intercepts a predeterminedarea of one spiral of projected rays such as 44 of the projected light and shadow image of the sound track on the recording, and transmits the results of fluctuations in light intensity or volume of the traveling projected sound track to a suitable amplifier II and thence to a sound translating device ll; the structures, functions, and operations of which are well known in the art and'are conventional equipment.

The screw 38 may have a pitch equal to the pitch of the projected spirals, under, which conditions the rotational speedsof the screw 38 and the recording holder 22 are equal, being driven by a very slow speed motor 41, or by a motorwith suitable speed reducer. As shown, the screw is driven direct, while the recording holder is driven from the screw through the miter gears 48, shaft ll, and gear Bil.

Obviously, the shorter the focal length of the lens II, the less will be the distance between the recording It and the photo-cell 43. Since the light passes only through an extremelynarrow slit, the focal length of the lens can be about equal to the length of theslit, in the case of 35 mm.

film about to 12 mm., with the distance from lens to, photo-cell being anywhere from five to thirty-five focal lengths.

In making the matrix, the blank can be rotated similarly to that of the recording in the reproducing unit just described, coupled with a diametric feed to produce the spiral sound track, and with the recording beam of vibratory mirror in a definite and fixed location.

, For ribbon recordings on 8, 16 or 35 mm. films,

the matrixmay be made as illustrated in Fig. .7,

with one, or with a plurality of different sound tracksin parallel. This matrix is then copied to a reduced scale indicated in Fig. 11 as diagrammatically illustrated in Fig. 12, in which sets .image of which is projected by the lens 58 through the slit 0! in the pressure plate 60 to the photo-sensitive emulsion II to a greatly reduced scale; the roller 0| being driven by suitable driving means, and in turn driving the roller 52 at a greatly reduced speed as indicated by the belt BI and sheaves l2 and II.

The reproducing unit for ribbon type record-' ings consists of a feed plate or platen 84 which has a slit 0! through which the image of the sound track It is projected through the lens 61 to the interceptor or photo-cell 88 as indicated at 00; the sound track, lens, and interceptor being in perfect alignment and the lens. Properly focused.

- This feed plate is slidably mounted in a support II as indicated at H and is-transversely'adiustable to bring the respective sound tracks, such as 00 and II in perfect registry with the axis of the lens and with the interceptor. by means of spaced screws" which are rotatable in bearings I4 on the support 10, and threadedlyoperable in threaded passages formed in the upright 15 on the platen 04. These two screws are coupled together for synchronous operation as indicated at II, by means of the knob or dial I1 which is provided with calibrations I. for coordination with the pointer ll, Therecording I is perfectly aligned between'the shoulders I and 01, ll being formed as a slot having a top wall functioning as a hold-down for the one edge of the recording; while the other side is held down and fed by suitable means such as the toothed rollers It and I4 and encompassing,

pierced band 8|, the teeth onthe rollers being sufiiciently long to pass through the band and engage the sprocket perforations It in the ribbon for positive driving-of the recording. The respective rollers 03 and are fixed on the respective shafts I! and 80 which are rotatable in tegral with the support II.

A suitable driv is provided and as illustrated" The interceptor or photo-cell is connected in H circuit with a suitable amplifier I! and sound translating unit 40.

The support 10 is integral with a standard II and integral base N on which the interceptor is moun in a fixed position. x

As in cated at II, the sound track is enlarged into a traveling light and shadow image, to a size preferablyabout equal tp that of the origi-, nally recorded sound track at the point I where the light and shadow image is intercepted by the photo-cell. The speed of travel and the area of the intercepted light and shadow image is therefore approximately equal to that of the original recording. v

The correct speed of travel of the recording is governed preferably by the resolving 'power'of the emulsion used. 'Graticular film iscapable of resolving about 500 lines per mm. which isequiv- I, alent to about 12,750 lines per inch. On this basis, the correct for a 6000 cycle track would be about 12- mm. or approximately tiinch per second, while for extreme fidelity at 10,000 cycles per second the correct speed would be about 20 mm. or approximately inch-per second. Micro-file film is capable of resolving about 230 lines per mm., which is equivalent to about 5,850 lines per inch. On the basis of 6000 cycles per second the correct speed would be about 26 mm. or approximately one inch per second, and for 10,000 cycles per seconiabout 4-4 mm. or approximately 1% inches per second.

The reduction from the matrix for Graticular riginal, thirty feed per second.

film would be on th order of 24:1 to 36:1, and for Micro-file film about 12:1 to 18:1, though any desired reduction not exceeding the previous maximums could be used. Speedsand reductions for other types of emulsions would be proportionate to their respective resolving powers.

In the case of Graticular film reduced to of the original matrix, the distance between the w lens 82 or 1 and the interceptor 43 or 88 should preferably be made equal to twenty-five focal lengths. In other words, the projection distance should be equal to the ratio of reduction plus one, multiplied by the focal lengthof the lens. However, this value may be increased or decreased as desired. 7

It will be-noted that if the original sound track is recorded at a lineal speed of 30 feet per second,

the recording made with a reduction of 24, then image of the sound track at the point of interception will have the same lineal speed as the I claim:

enlarged 24 times, the traveling light and shadow 1. Sound reproducing apparatus comprising; I

a first support; a lens mounted on one side of said support and a source of projection illumination mounted on the other side; meansrotatably mounted on said firstsupport between said lens and said source of projection illumihation. for

supporting a disc-type photographic recording in the focal plane of said lens; a second support in spaced relation to said first support; a photo-cell located in the object plane of said lens and radially adjustable on said second, support; and driving means for driving said means rotatably mounted at uniform speed and simultaneously radially adjusting said photo-cell at a speed '00- ordinated to the speed of radial travel of the projected image of the sound track on the disctype recording.

2. A structure as defined in claim 1; said means .rotatably mounted comprising a ring gear peripherally supported and having means for peripherally securing a disc-type recording thereon;

said driving means for radially adjusting said photo-cell comprising a screw and a guide bar ".mounted on said second support in parallel and a lens; means for supporting and rotating a disctype photographic sound recording having a spiral sound track, in the focal plane of said lens,

3. Sound reproducing apparatus comprising;

and means for illuminating said record; a photocell radially adjustable relative to the axis of a projected image of said sound recording and 2,sa4,1a1.. r 7

located in'the object plane of said lens; driving means for rotating said means for supporting, and for radially adjusting said photo-cell in coordination with the speed of radial travel of the projected image of the sound track, and amplifying and sound translating means in circuit with said photo-cell.

4. A structure as defined in claim 3; [said means for supporting comprising; agear member which islight-transmitting throughout the area of the soundtrack on the recording to permit passage of light therethrough to said lens; said means for radially adjusting said photo-cell comprising a guide bar and a screw mounted in parallel, and a support slidable on saidbar and having a halfj-nut for threaded cooperation with said screw for adjusting and for convenient manualreturn of said support slidable to a starting position, a gear for saidscrew; said driving means including a gear connection to said gear member and to said gear for saidscrew.

5. Sound reproducing apparatus for disc-type photographic recordings having a spiral sound track comprising; a lens; rotatable supporting means for supporting a recording in the focal plane of said lens and permitting passage of light therethrough to said lens, and illuminating means for said recording; a photocell located-in the object plane of said lens, and driving means for said rotatable supporting means and torsimultaneously adjusting said photo-cell in conformity with the speed of radial travel of the projected image of the sound track of the recording, and including means for manual return of said photo-cell to starting position at will; and

amplifying and sound translating means in circuit with said photo-celli 6; Sound reproducing apparatus for disc-type photographic recordings having a spiral sound between said lens and said source of illumination and forming means for peripherally supporting a recording while permitting passage of light through the recorded area to said lens; a base; a slide bar and a screw mounted onwsaid base in parallel and radially relativeto the axis of said gear; a second support slidable on said bar and CLIFFORD n PRICE.

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