US2599312A - Phonograph stylus - Google Patents

Description

June 3, 1952 J. ANDRES PHONOGRAPH STYLUS Filed ma 20, 1950 F IG. 2.

IN V EN TOR.

Patented June 3, 1952 TENT OFFICE PHDNOGRAPH STYLUS 'LloydjJ'rAndres, Chicago, Ill., assignorto Perms, Incorporated, Chicago, 111., a corp oration ApplicationMay 20, 1950,, .Serial'No. 163. 365

4 Claims.

This invention relates in general to phonograph styli and more particularly to a new and novel construction for securing a playing point in a needle member with a jacket applied to the point and end portion of the needle member for the dual purpose of added security in bonding the point to the-member and provision for resistance to damage from shock.

Prior to this invention small playing points, particularly sapphires, were secured in needle members by means of a metallic bushing surrounding the point and inserted in a .hole in the member, whereupon the bushing was swaged or spun to provide a bond to secure the point in the needle member. This construction inherently provides excessive undesirable mass at the end of the needle member andrequires a bushing of ex ceedine'ly precision dimensions and the exercise of-great care in swaging or spinning and because of the relatively large forces required to deform the bushing a large number of points are damaged or fractured during assembly.

The present invention overcomes the above and. other difiiculties through the provision of a novel construction and a method of assembly which inherently provides desirable low mass and is adapted to low cost manufacture with a minimum possibility of damage to the playing point during assembly and in addition the jacket surrounding the playing point and end of the needle member provides a high degree of resistance to damage from impact shock during use, thus making possible improved reproduction and extension of the useful life of the playing point.

These and other objects and advantages in one embodiment of the invention will be apparent from the appended description and drawings in which:

Fig. 1 is an enlarged fragmentary side elevation of a needle member with the playing point positioned in the end portion thereof and showing a protective bonding material covering said end portion and playing point.

Fig. '2 .is a plan view of the needle member shown Fig. 1.

Fig. 3 is a greater enlarged plan view of the end portion of the needle member shown Fig. 2 before theinsertion of the playing point.

Fig. 4 is a cross-sectional side view of the playingfportlon taken through section line 4-4, Fig. 3.

Fig. 5 is the same as Fig. 3 after the insertion of the playing point and before the protective bonding material shown Fig. 1 is applied.

Referring to Fig. l, a needle member I, which is usually made of resilient wire or formed from sheet metal, is adaptedat the broken-ofl'.end to be joined to a shank or otherwise securedto 'a transducer, not shown, and in order to assure wide range reproduction in coacting with a transducer the member must be of low mass construction. Metals such as spring steel, Phosphor bronze, beryllium copper and nickel base alloys provide proper elasticity from a needle compliance standpoint and also the desired degree of tensile characteristics for retaining relatively hard playing points such as jewels therein in accordance with the construction hereinafter described.

For the purpose of this description and of illustrating acceptable proportions the wire member and the playing point I will be considered as having diameters of .015 inch and the end portion 2, shown Fig. 3, is flattened by well-known means to a thickness of approximately .0075 inch to provide a petal having two parallel plane surfaces. It is apparent that an equivalent needle member of proper thickness may be blanked from sheet metal.

Referring to Figs. 3 and 4, a trapezoidal hole is pierced through the center of the end portion 2 normal to its surface and die formed to provide a plurality of inner contact surfaces 3, with a portion of said surfaces having a conical shape with respect to axis y-y. A portion of the displaced metal is formed into a flange 4-4 around the pierced hole on the underside of the end portion, as shown.

The cylindrical playing point 5, shown Fig; '1, having a conical tip terinating in a radius 6 for engaging a record groove is machine pressed into the hole in the end portion and in so doing the contact surfaces 3 are further formed into tight cylindrical contacts 3-00 with the playing point as shown in Fig. 5, leaving a plurality of open spaces or apertures 1- between the side wall of the playing tip and the "inner wall of the hole.

It is to be noted that the press-fitted portions of the flange 4 will exert high pressure contact to the cylindrical wall of the playing point normal to the axis y-y, which serves to hold the point in place. The inward pressure afforded by the 3-a portions of the flange 4 is augmented by tension stresses, illustrated by arrows 8+8, set up in the side portions of the end portion '2.

Although the trapezoidal hole shown in Fig. 3 is a preferred form, good results are obtained when a circular hole having the same general cross section contour as shown in Fig. 4 is used, provided playing points having precise diameter tolerances are used.

To further reinforce the frictional bond between the playing point 5 and the end portion 2 and to provide a protective jacket or coating 9 to minimize damage to the playing portion from impact, the end portion and the playing point are coated with one of a number of compatible solders or cements. A particular coating adapted to low mass requirements has been found to be thermosetting Bakelite cement, which is applied as a liquid and changed to a solid by the application of heat. The cement coating may be applied by dipping or spraying the end portion of the needle member and permitting the material 'to dry with the playing point uppermost; thus excessive coating material will drain by gravity from the radius of the playing point. However, the presence of a relatively thin coating on the radiused surface of the playing point will not interfere with proper playing in contact with a record since the exceedingly high unit pressures encountered will quickly abrade away any excessive coating material.

It is apparent that a fillet of the coating 9 will surround the playing point at the upper and lower surfaces of the end portion 2 and a homogeneous junction of the two fillets will be made through the apertures 1, shown Fig. 5, thus providing the equivalent of a washer on each side of the end portion around the playing point joined by a plurality of dowels through the apertures 1.

Thus small fragile playing points are economically and firmly secured in phonograph needle members with inherent protection from accidental impact or shock.

Having described my invention I claim:

1. A phonograph stylus comprising a resilient metal needle member adapted at one end to be secured to a transducer and having a fiat portion at its opposite end, said flat portion having a hole therethrough substantially symmetrical about an axis located in the longitudinal center of and normal to said flat portion, a flange integral with and projecting from the lower side of said flat portion positioned in coaxial relation with said hole, the lower portion of the wall of said hole symmetrically spaced parallel to. said axis and substantially coaxial with said flange, the upper portion of the wall of said hole symmetrically divergent away from said axis, a cylindrical playing point secured in said hole substantially coaxial with said axis with its outer surface in intimate contact with the said lower portion of the wall by the stresses exerted by said flange, a coating means in adhesive contact i and effectively covering said fiat portion and said playing point.

2. A phonograph stylus comprising a resilient metal needle member adapted at one end to be secured in a transducer and having a flat portion at its opposite end, said fiat portion having a hole therethrough substantially symmetrical about an axis located in the longitudinal center of and normal to said fiat portion, a flange integral with and projecting from the lower side of said flat portion positioned in coaxial relation with said hole, the lower portion of the wall of said hole symmetrically spaced parallel to said axis and substantially coaxial with said flange, the upper portion of the wall of said hole symmetrically divergent away from said axis, a cylindrical playing point secured in said hole substantially coaxial with said axis with its outer surface in intimate contact with the said lower portion of the wall by the stresses exerted by said flange.

3. A phonograph stylus comprising a resilient metal needle member adapted at one end to be secured in a transducer and having a flat portion at its opposite end, said flat portion having a polygonal hole therethrough substantially symmetrical about an axis located in the longitudinal center of and normal to said flat portion, a flange integral with and projecting from the lower side of said fiat portion positioned in coaxial relation with said hole, the lower portion of the wall of said hole symmetrically spaced parallel to said axis and substantially coaxial and concurrent with said flange, the upper portion of the wall of said hole symmetrically divergent away from said axis, a cylindrical playing point secured in said hole substantially coaxial with the said axis with its outer surface in intimate contact with a plurality of surfaces of the said lower portion of the wall providing a plurality of spaced apertures between the said wall of the said hole and the outer surface of the said cylindrical playing point, a coating means in adhesive contact and effectively covering the junctions of said playing point with both sides of said flat portion and filling said apertures.'

4. A phonograph stylus comprising a resilient metal needle member adapted at one end to be secured in a transducer and having a flat portion at its opposite end, said flat portion having a polygonal hole therethrough substantially symmetrical about an axis located in the longitudinal center of and normal to said flat portion, a flange integral with and projecting from the lower side of said fiat portion positioned in coaxial relation with said hole, the lower portion of the wall of said hole symmetrically spaced parallel to said axis and substantially coaxial and concurrent with said flange, the upper portion of the wall of said hole symmetrically divergent away from said axis, a cylindrical playing point secured in said hole substantially coaxial with the said axis with the said lower portion of the wall providing a plurality of spaced apertures between the said wall of the said hole and the outer surface of the said cylindrical playing point.

LLOYD J. ANDRES.

REFERENCES CITED The following references are of record in thev le of this patent:

UNITED STATES PATENTS

Images