US2347623A - Sound record and method of making - Google Patents

Description

April 25, 1944. w 2,347,623

SOUND RECORD AND METHODOF MAKING Filed Sept. 15. 1941 3 Sheets-Shee t 1 i i 15 1 i5 15 l I r5} I8 .17'. 18 P 7 i B) April 25, 1944. R! WAGNER 2,347,623

SOUND RECORD AND METHOD OF MAKING Filed Sept. 15. 1941 3 Sheets-Sheet 3 TOR,

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Patented Apr. 25, 1944- SOUND RECORD AND METHOD OF MAKING Robert Wagnenflew York, N. Y., assignor to The Dow Chemical Company, Midland, Micln, a corporation of Michigan Application September 15, 1941, Serial No. 410,945

8 Claims.

This invention relates to a method of makin a sound record, and to the-product thereby obtained.- It relates in'particular to a method which produces, in a sound record, whether a disc, film or cylinder, a laterally modulated groove the groove beneath that plane.

filed July 5, 1940.

the reproducing needle.

surface for reproducing needles.

are contemplated as well.

ciple of the invention may be used.

throughout to designate like parts.

Figs, 1-8, inclusive, are views partially in perspective, showing positions of a recording stylus for use in the invention, successive figures showing the same stylus, rotated about its longitudinal 5 axis by successive increments of 45; or sound track having a shoulder on one side Fig. 9 is a plan view of a typical disc-form recthereof raised above the planeof the record ma- 0rd havingclockwise rotation, and showing, in terial a distance at least as great as the depth of greatly enlarged and exaggerated form, crosssectional views of the recording stylus, taken This application is a continuation-in-part of 10 along lines I-I, II--1I, III-III, etc. VIII- my co-pending application Serial No. 344,002, VIII, in Figs. l-8, respectively, inclusive;

Fig. 10 is a cross-sectional view of a portion of Several methods of recording sound have been, the new sound record made according to the developed and are conventional in the art. The method of the present invention; commonest method in use today is a lateral cut- Fig. 11 is apart sectional, part perspective view ting method. Its principal disadvantage lies in of one type of sound track formed according to the fact that this method of cutting records has and embodying the invention; always been accompanied by the formation of Fig. 12 is a view of a stylus suitable for use in shavings, cuttings, threads, or other debris which the'method of the invention; must be wiped or brushed from the record surface Fig. 13 i a re y en iew, in V ic as they are formed, and which-constitute a 'needelevation, of a. tip of a recording stylus, turned less waste of material and are a considerable inthe position shownin Fig. 5; and cause of inconvenience. 'Another disadvantage Fig. 14 is a plan view of the working tip of of the customary record, made by lateral cutthe stylus shown inFig. 13. ting methods, is the well-known tendency of the In practicing the present invention, a laterally reproducing needle to jump from one shallow modulated soundtrack is formed by a concurgroove an another, due to the constant inward rent cutting and embossing operation performed thrust of the reproducing head on a typical disc on a disc, roll, or strip or a. tough and flexiblerecord, for example, and to the failure of the record material, in such manner that no shavcustomary grooves to provide lateral support for ings, scrapings, or other debris are separated from the record material, and that the surface of the It is accordingly among the objects of the material i slit at an acute angle thereto to form invention to provide a method of recording a continuous flap which is displaced laterally and sound, particularly by lateral modulations, whereupwardly from the sound track groove to form by the shavings, cuttings, or other debris incia substantial ridge or shoulder extending above dent to known practice are eliminated. Another the plane of the body of the material, integral object is to provide a method of recording sound at its base with that material. whereby the sound track produced is capable of According to one embodiment of the invention, providing substantial lateral support and contact the foregoing and related objects may be attained Articles inci- 40 byiising in a'particular novel manner a recording dent to the method of .the'invention, a general needle heretofore, known and used only for hilladvance in the art, and other and related objects, and-dale recordings. Such a needle, or stylus l5,

- is shown in Figure 12, and is described in U. S. To the accomplishment of the foregoing and Patents 1,918,271 and 2,018,496. The stylus, per related ends, the invention, then, consists of the se, forms no part of the present invention, though method and product hereinafter fully described the particular manner of its use is of considerable and particularly pointed out in the claims, the importance. For an understanding of themeannexed drawings and the following description ferred embodiment of the invention to be desetting forth in detail one mode of carrying-out scribed below, it is necessary first to describe 1 the invention, such disclosed mode illustrating, 5o briefly the principal features of the preferred styhowever, but one of the ways in which the prinlus. The recording stylus l5 may have its working tip formed of steel, sapphire, or other suit- In the said annexed drawings, forming a part able hard material and comprises a shank or hereof, wherein like reference characters are-used body portion I6 and a tip or head II. In the I! preferred form the tip i1 is the acute'frustum of a cone, and preferably of a right cone, as illustrated in Fig. 13. The tip I1 therefore presents a flat face i8 of elliptical contour, as is evident from Figs. 12 and 14.

The material operated on, i. e., that of which the record blank is composed, likewise forms no part of the invention, except as its properties may be important. The material used may be a cellulose ester or cellulose ether, or one of to a fiat, circular disc record, but is not to be limited thereto, as it is clearly applicable as well to recording sound on film strips or loops, or on cylinders.

When preparing a sound record according to the method of the present invention, a fiat circular disc I9, which may have at least a surface coating of ethyl cellulose or similar flexible and non-brittle material, is first provided. .Such a disc is placed upon a conventional turntable, not shown, and a stylus III of the type above defined is addressed to the periphery of the disc. The stylus I is secured in the cutting head of a lateral modulation recording machine (also conventional in the art and not shown) so mounted on a carriage that, as the turntable rotates beneath it, the carriage moves on a radial line toward the center of the disc, thus providing a spiral groove. The relationship between the rate of rotation of the turntable and the radial movement of the cutting head can be adjusted in known manner to form any desired number of grooves per radial inch. During conventional operations on disc-form records, the distance between successive convolutions is constant. The construction and operation of recording machines, being well known in the art, will be understood without further detail.

It is apparent that the recording stylus I5 may be addressed to the record I9 in any of several positions of its fiat elliptical face with. respect to the oncoming record. Figs. 1-8, inclusive, illustrate eight typical positions of the tip I! of the stylus, differing from one another by a rotation of the stylus I5 through successive angles of 45. The same positions of the stylus IS with respect to the oncoming record are illustrated in plan in Fig. 9. Not all of the positions illustrated are effective for use in the present invention, and, of thosewhich are operative, certain positions are preferred over others. referring to Fig. 9, when the stylus I5 is positioned on the disc IS with the plane of the elliptical face l8 in alignment with the path of the oncoming record, as in positions I and V,

the stylus I5 splits or tears the record It and attempts at reproduction give, at best, very unfaithful results. There is no well defined groove along which the play-back needle can track. for

sound reproduction. If the stylus I5 is positioned with its fiat elliptical face l8 at right merely scratches the surface of the film l9, gouging out occasional pieces or threads of the material of which the record is made. In position VII, wherein the elliptical face I8 of the stylus I5 is the trailing edge, the stylus l5 behaves morenearly like the customary cone-tipped needles and cuts a continuous thread which must be brushed aside from the record surface before attempts can be made at reproduction. The usual disadvantages of past practices with other forms of stylus are attendant upon the use of the herein described stylus IS in positions III and VII.

It is the discovery upon which the preferred embodiment of the present invention resides that when the stylus I5 is positioned with its flat elliptical face I8 neither in alignment with, nor vertical to, the path 20 of the oncoming record I9, 1. e., when it is in any of the positions H, IV, VI, or VIII, the stylus I5 does not scratch or tear the record I9, nor does it cut a thread, but rather it partly cuts or slits the material of the record blank at an acute angle to its surface along the path 20 of the sound track 2|-, providing a flap 22, integral at its base with the main body of the record l9, and movement of the record l9 past the recording stylus I5 in any of these positions displaces the material forming said flap 22 laterally and upwardly to form an upstanding ridge or shoulder (also designated by reference No. 22) raised above the plane 23 of the material on one,side only of the groove 2!. To any of positions 11, IV, VI, or VIII a high shoulder 22 is formed on one side of the groove 2| as is shown, for example, in Figs. 10 and 11. This shoulder 22 is of particular advantage during the play-back operatiorp since it provides a greater contact surface between the record material and the reproducing needle than has been,.avail'able in the records of the prior art. The reproducing needle, therefore, rides freely along a relatively shallow groove 2| and against the raised shoulder 22.

The stylus in positions II and VIII throws the shoulder 22, above-described, to the right or outside of the groove 2| (when facing the oncoming record). In positions IV and VI it throws the shoulder 22 to the left or inside of tions VI or VIII, with the flat face I8 trailing.

Thus,

the groove 2|, and it is the result of a stylus I5 in position VI, which is illustrated in Figs.

10 and 11. c

"When the stylus III is in either of positions II or IV, its flat face It is the leading face, and

greater recording pressures are required to produce a groove 2| of the same depth and fidelity as can be obtained when the stylus I5 is in posi- When the disc records [9 are of the conventional outside-in type, it is preferred that the raised shoulder 22 be disposed toward the center of the disc, thereby to provide at least partial support for the reproducing needle which will tend to be pulled toward the ce'nterof the record by the motion of the record and of the reproducing head. Since most records are of the outside-in type, by far the best results for most purposes have been attained through the use of the stylus I5 in position VI. If, however, the record is.

.of the inside-out" type, or ifit is a cylinder record such as that employed in dictation machines, where the recording stylus I5 moves from left to right and the thrust of the reproducing needle likewise may be from left to right, it may I often be desirable to have the raised "shoulder 22 case, owing to the lower recording pressure required, position VIII of the stylus l has been found most effective.

The operation has been outlined with reference to the recording stylus 15 positioned with its fiat elliptical face It at an angle of 45, 135, 225, or 315 to the path 20 of the oncoming record l9. These particular values have been given-by way of illustration, it being understood that similar results are obtained when the stylus I5 is rotated by about 35 either way from the suggested positions. The harder the recording composition, the greater is the permissible variation from the preferred positions, but in no case can the stylus be within of any of positions I, III, V, or VII. Thus, position VI is illustrated as being one wherein the flat face ll! of the recording stylus I 5 is at I an angle of 315 to the path 20 of the record I!) passing beneath it. Very similar and substantially as satisfactory results are obtained when the stylus I5 is positioned with its fiat face I8 at any angle between 280 and 350 to the path 20 of the oncoming record. Similarly, the stylus I5 in position VIII may be turned with its face 18 at an angle between 190 and about 260 to the path 20 of the record.

The specific method, therefore, which is at present representative of the preferred form of the invention, is one of making a laterally modulated sound record in tough material which is flexible and non-brittle in thin section, which comprises addressing a stylus to the surface of the record blank with its longitudinal axis at an angle thereto which may be selected between the vertical and a 10 drag therefrom, said stylus having a working tip which is an acute frustum of a cone, said tip being positioned for recording with the fiat face of the frustum at an angle of M45) i35 with respect to the path traversed by the blank in passing the stylus, n being an odd integer, and moving the blank while imparting sound impulses thereto through the stylus in known manner, thereby slitting the surface of the-record at an acute angle thereto along the path of the sound track to provide a partially severed portion, continuous at its base with the main body of the record, and displacing the partially severed portion laterally and upwardly to form a substantial upstanding ridge raised above the plane of the record, continuous with, and on one side only of the concurrently formed groove. V

Referring now to Figs. 13 and 14, it will .be observed that aniong the variables which are of importance to the structure of the working tip H of the recording stylus l5 are the angle A of the cone of which that tip ll is a part, the angle B stances just enumerated, the cutting tip I! will tend to cut into the record to a lesser extent than when a more acute angle B is employed. It is not the province of the present application to discuss all possible variations in the recording stylus l5, but it may be said that very satisfactory results have been obtained employing a recording stylus l5 whereof angle A may lie between 22 and about 60, but preferably is about 24; angle B is at least 30, is not over 80, and preferably is 37 to 45;

.and distance H is of the order of 0.03 to 0.08 inch.

Numerous variations in the specific needle tip I! may, of course, be employed.

In 'a specific example, a film of ethyl cellulose of about 46 per cent ethoxy content, and 0.015 inch thick, was provided in the form of a circular disc I!) having the customary center holes 24 for positioning the disc on a turntable of a lateral modulation recording machine. The machine employed was adapted to make an outside-in cut with about 80 grooves per radial inch. The recording stylus l5 was mounted nearly vertical to the recording medium 19, dragging by a few degrees. The tip ll of the stylus had an angle A of about 24, an angle B of about 40, and a distance H of about 0.045 inch. Angle 0 was chosen as 315", i. e., the stylus l5 was addressed to the record I9 with its fiat elliptical face 18 in position VI. Sound was conveyed through the recording machine to the film H! by electr'o-duplication from another record. A faithful reproduction was obtained on play-back. The record was then cut to obtain a small piece which was then mounted, in known manner, in a microtome, and thin sections were made and mounted on microscope slides. Photomicrographs were made, showing clearly the cross-sectional shape of the sound tracks herein reproduced in Fig. 10. The grooves 2| were found to extend 0.0015 inch below the plane 23 of the record 19, and to be about 0.004 inch wide. The upstanding shoulders 22 projected above the plane 23 of the record 19 about 0.0033 inch, and were about 0.0015 inch thick at their juncture with the main body of the film.

The method herein described may be adapted easily for use with any of the conventional lateral modulation sound recording systems on the market. The cutting head of the various machines need only be adjusted so as to cooperate with the shank portion I6 of the recording stylus l5 to position that stylus with its fiat face l8 at the proper angle within one of the 90 arcs between alignment with the path of the oncoming record and a/line at right angles thereto.

The invention has been described with respect to the use of a particular type of stylus as the means of forming the novel sound track of the invention. Other means may be devised for forming a track of this description. Thus, for

example, if the conical stylus tip is truncated parallel to an element of the cone, a flat face of parabolic contour may be formed which is operative in the same manner as the elliptical faced tips described above. Similarly, a stylus tip of hyperbolic contour may be made in known manner, and used as described. It is, therefore, to be kept in mind that the description and example above given are purely illustrative, and that the inventor does not limit himself thereto, ex-

. cept as indicated in the following claims.

I claim:

1. A method of making a sound record in tough material which is flexible-and non-brittle in thin section, which comprises slitting the surface of the record at an acute angle thereto along the path of the sound track to provid a partially severed portion, continuous at .1 its base with the main body of the record, and displacing the partially severed portion laterally and upwardly to form a substantial upstanding ridge raised above the Plane of the record, continuous with, and on one side only of the concurrently formed groove.

2. A method of making a sound record in a disc having a surface of a tough material which is flexible and non-brittle in thin section, which comprises slitting the surface of the record at an acute angle thereto slanting inwardly toward the center of the disc along the spiral path of the outside-in sound track, to provide a partially severed portion, continuous at its inwardly disposed base with the main body of the record, and displacing the partially severed portion inwardly and upwardly to form a substantial upstanding ridge raised above the plane of the record, continuous with, and on one side only of the concurrently formed groove.

3. The method of making a laterally modulated sound record in tough material which is flexible and non-brittle in thin section, which comprises addressing a stylus to the surface of the record blank with its longitudinal axis at an angle thereto which may be selected between the vertical and a 10 drag therefrom, said stylus having a working tip which is an acute frustum of a cone, said tip being positioned for recording with the flat face of the frustum at an angle of n(45) :35 with respect to the path traversed by the blank in passing the stylus, n being an odd integer, and moving the blank while imparting sound impulses thereto through the stylus in known manner, thereby slitting the surface of the record at an acute angle thereto along the path of the sound track to provide a partially severed portion, continuous at its base with the main body of the record, and displacing the partially severed portion laterally and upwardly to form a substantial upstanding ridge raised above the plane of the record, continuous with, and on one side only of the concurrently formed groove.

4. The method of making a laterally modulated sound record in tough material which is flexible and non-brittle in thin section, which comprises addressing a stylus to the surface of the record blank with its longitudinal axis at an angle thereto which may be selected between the vertical and a 10 drag therefrom, said stylus having a working tip which is an acute frustum of a cone, said tip being positioned for recording with the flat face of the frustum trailing at an angle of n(45) i35 with respect to the path traversed by the blank in passing the stylus, n being one of the integers and 7, and moving the blank while imparting sound impulses thereto through the stylus in known manner, thereby slitting the surface of the record at an acute angle thereto along the path of the sound track to provide a partially severed portion, continuous at its base with the main body of the record, and displacing the partially severed portion laterally and upwardly to form a substantial upstanding ridge raised above the plane of the record, continuous with, and on one side only of the concurrently formed groove.

5. The method of making a laterally modulated sound record in tough material which is flexible and non-brittle in thin section, which comprises addressing a stylus to the surface of the record blank with its longitudinal axis at an angle thereto which may be selected between the vertical and a drag therefrom, said stylus having a working tip which is an acute frustum of a cone, said-tip being positioned for recording with the flat face of the frustum leading at an angle of n (45) i35 with respect to the path I traversed by the blank in passing the stylus, n

being one of the integers 1 and 3, and moving the blank while imparting sound impulses thereto through the stylus in known manner, thereby slitting the surface of the record, at an acute angle thereto along the path of the sound track to provide a partially severed portion, continuous at its base with the main body of the record, and displacing the partially severed portion laterally and upwardly to form a substantial upstanding ridge raised above the plane ofthe record, continuous with, and on one side only of the concurrently formed groove.

6. The method of making a laterally modulated sound record in tough material which is flexible and non-brittle in thin section, which comprises addressin a stylus to the surface of the record blank withits longitudinal axis at an angle thereto which may be selected between the vertical and a 10 drag therefrom, said stylus having a working tip which is an acute frustum of a cone, said tip being positioned for recording with the flat face of the frustum trailing at an angle of 3l5i35 with respect to the path traversed by the blank in passing the stylus, and moving the blank while imparting sound impulses thereto through the stylus in known manner, thereby slitting the surface of the record at an acute angle thereto along the path of the sound track to provide a partially severed portion, continuous at its base to the left of the oncoming sound track to the main body of the record, and displacing the partially severed portion laterally and upwardly to form a substantial upstanding ridgeraised above the plane of the record, continuous with, and on the left side only of the concurrently formed groove.

7. The method of making a sound record in tough material which is flexible and non-brittle in thin section, which comprises addressing a stylus to the surface of the record blank with its longitudinal axis at an angle thereto which may be selected between the vertical and a 10 drag therefrom, said stylus having a working tip which is an acute frustum of a cone, said tip being positioned for recording with the fiat face of the frustum trailing at an angle of 225i35 with respect to the path traversed by the blank in passing the stylus, and moving the blank while imparting sound impulses thereto through the stylus in known mannenthereby slitting the surface of the record at an acute angle thereto along the path of the sound track to provide a partially severed portion, continuous at its base to the right of the oncoming sound track to the main body of the record, and displacing the partially severed portionlaterally and upwardly to form a substantial upstanding ridge raised above the plane of the record, continuous with, and on the right side only of the concurrently formed groove.

8. A sound record having a laterally modulated sound track consisting of a spiral groove of substantially uniform depth throughout its length and, immediately adjacent thereto and on one side only thereof, a substantial ridge projecting above the plane of the record a distance at least as great as the-depthof the groove below said,

plane and formed from the material displaced

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