US1984637A - Diaphragm device - Google Patents

Description

Dec. 18, 1934. E H: FOLEY Er AL 1,984,637

DIAPHRAGM DEVICE Original Filed April 29, 1925 36w GUI B. swim/ EARL, H. FULE'K Patented Dec. 18, 1934 DIAPHRAGM DEVICE Earl H. Foley; Seattle, and Guy B. Sampair, Tacoma, Wash, assignors, by direct and mesne assignments, to Filmtone Corporation, a corporation of Delaware Application April 29,

1925, Serial No. 26,797

Renewed May 12, 1934 2 Claims.

Our invention relates broadly to improvements in sound recording and reproducing instruments of the diaphragm type, and more particularly it is our purpose to provide a device of this character wherein means are employed of a unique nature for intensifying the action ofa diaphragm upon a stylus under the influence of sound waves directed thereupon.

Heretofore, in devices for recording and reproducing sound'of the type wherein a diaphragm has mounted thereon a cutting stylus, it has been usual to mount the stylus at the central point of the diaphragm. When so mounted, however, it has been found that the relatively high degree of resistance offered by the recording medium or record body to the movement of the cutting stylus when actuated by the vibrations of the diaphragm serves to dampen the movement of the diaphragm at the point of contact of the stylus with the diaphragm thereby allowing a large proportion of the force of the sound vibrations to be dissipated through the elasticity which exists in the unsupported portion of the diaphragm between such central point whereon the stylus is mounted and the periphery supported by the diaphragm housing. In our present invention, however, advantage is taken of the movement of that portion of the diaphragm between the central portion and the periphery by providing a plurality of points of contact between the cutting stylus support and the diaphragm, thus greatly reducing the unsupported area of the diaphragm and hence greatly reducing the elasticity and consequent movement of what has heretofore been the unsupported portion, and at the same time transmitting a far greater force to the cutting stylus than is the case where only one point of contact between the stylus and the diaphragm is employed. Experience has demonstrated that the best results are obtained with the conventional type of recorder when the diaphragm used has a relatively small diameter; this being due to the fact that the unsupported area of the diaphragm is thus reduced and the dissipation of movement of the diaphragm through the elasticity of the unsupported area thereof curtailed. At the same time with diaphragms of such a relatively small diameter, there is encountered the decided disadvantage of the lesser movements of the smaller diaphragm when acted upon by sound waves, thus rendering more feeble the action of the cutting stylus and limiting the type of effective recording material to that of a relatively soft and plastic nature. In our present improved recorder a diaphragm of an area many times that which has been heretofore thought possible is employed, thus greatly intensifying the movements of the cutting stylus and permitting clear and accurate recording of sound on materials which have previously been considered too hard.

To these and other equally important ends our invention consists in the construction, combination and arrangement of parts described hereinafter, but interpretation of the scope of the invention should only be conclusive when made in the light of the subjoined claims.

One embodiment of our invention, and several minor modifications thereof are represented by way of example in theaccompanying drawing, wherein;-

Figure 1 is a bottom plan view of a diaphragm provided with our four point spider,

Figure 2 is a sectional side elevation, the device being inverted, of the type of recorder having a spider such as is shown in Figure 1,

Figure 3 is a view similar to Figure 2 of the four point spider type, but the stylus carrying member is here of a slightly modified form,

Figure 4 is a view of a preferred type of diaphragm casing which is adapted to insure a greater constancy in pressure on a recording medium,

Figure 5 is a side elevation, partly broken away, showing a modified form of stylus carrying member, and

Figure 6 is a top plan view of a modified form of stylus supporting spider having eight points.

Like characters of reference are used to designate like or similar parts in the several views of the drawing, in which;

The diaphragm casing is designated (1) and is circular in configuration, and annularly flanged as at (2). Centrally of the casing is provided a flanged opening (3) through which the sound impulses or waves are delivered.

Mounted on the flanged portion (2) of the casing and secured in place by suitable gaskets (4) is a diaphragm (5), and carried upon the diaphragm is a spider (6) formed with four radial legs (7) terminating in feet (8). The central portion or crown (9) of the spider is spaced from the diaphragm and in attaching the spider to the diaphragm any suitable cement may be used. An optional form of my spider is shown in Figure 6 in which eight legs are used, the alternate legs (7) being shorter. Formed on the crown of the spider is a post (10). The post (10) and the feet (8) of the legs (7) all contact with the diaphragm and serve to convey simultaneously from the various areas of the diaphragm the movements of the same under the influence of sound waves delivered thereto. A stylus (11) is mounted on the crown (9) and extends angularly therefrom into contact with a record body (not shown). Obviously the device may be utilized with equal facility either to record or reproduce sound but in the present instance it is believed that a detailed description of the process of recording will sufiice.

In Figure 3 of the drawing is illustrated a modified form of mounting the stylus in which lever action is utilized to increase its efiectiveness. In this form an arm (12) is pivotally attached as at (13) to the crown (9) of the spider (7) and midway of its length it is fulcrumed as at (14) on a post (15) carried by the flanged portion (2) of the casing. The stylus (11) is carried on the free end of the arm. In Figure 4 an optional form of diaphragm casing is shown, and such form exemplifies the use of an interior supplementary casing member (16) which carries the diaphragm, and which is spaced from and chambered in the exterior casing, and connected thereto by a suitable hinge (17) so that a constant pressure may be exerted upon a record body during the production (or reproduction) of a record. The form of casing may be used with any of the embodiments of my diaphragm or stylus carrying member.

In Figure another modified form of stylus carrying member is shown in which lever action is utilized; Here the arm (18) is pivoted to the casing as at (19) and fulcrumed on the crown of the spider as at (20), and is formed with a plurality of longitudinally aligned, spaced, screwthreaded openings (21) in any of which the angular stylus carrying member (22) may be placed for retention. The movement of the stylus under the influence of the diaphragm is obviously inversely proportionate to the distance of the member (22) from the free end of the arm, and directly proportionate to its proximity with the pivoted end (19) of the arm.

In operation, sound waves are introduced into the casing through the opening (3) therein by means of the usual tube or horn (not shown); these waves strike the diaphragm (5) causing it to vibrate; the vibrations are transmitted to the legs of the spider (6) and thus impart a vibratory movement to the cutting stylus through crown (9). This movement is of course translated into a record groove in any suitable record material which may be passed beneath the cutting stylus. Whether the record grooves designed to be out are of the vertical or horizontal type is immaterial since my device will out either kind with equal effectiveness and upon material of any reasonable hardness. In the event that it is desired to reduce the extent of movement of the stylus under the influence of the diaphragm, or increase the magnitude, this can be accomplished by varying the position of the stylus carrying member (22) on the arm (18). It has been found that our present recording diaphragm will function with materials of great hardness, and the simplicity of the device as a whole commends it.

While in the foregoing there has been illustrated and described such combination and arrangement of elements as constitute the preferred embodiments of our invention, it is never.- theless desired to emphasize the fact that interpretation of the invention should only be conclusive when made in the light of the subjoined claims.

Having described our invention and its objects with such attention to detail as will thoroughly acquaint one skilled in the art with its construction and advantages, we claim:

1. In a sound recorder, the combination of a housing, a diaphragm mounted therein, a cutting stylus, a cutting stylus carrying member hingedly mounted on said housing, said member having a plurality of points whereon said cutting stylus can be mounted, means for communicating movements of said diaphragm to said stylus carrying member, said means having a plurality of points of contact with said diaphragm.

2. In a sound recorder the combination of a support comprising a housing, a large diaphragm mounted in said housing, a stylus carrying member hingedly mounted on said support, means connected to one point of said member for communicating movements of said diaphragm to said member, said means having a plurality of points of contact with said diaphragm, a cutting stylus secured to said member at a point closer to the pivotal support of said member than the said one point and said member having means located at a point differently spaced from said pivotal support for securing a stylus thereto.

GUY B. SAMPAIR. EARL'I-I. FOLEY.

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