US2505715A - Phonograph needle - Google Patents

Description

W 25 19550 M. A. MILLER PHONOGRAPH NEEDLE Filed April 17, 1946 INVENTOR.

Patented Apr. 25, V195() AUNITED STATES PATENT GFFICE' 2 Claims.

My invention relates to a metallic needle for` tracking in the grooves of a phonograph disc record. More particularly, I am here concerned with certain details having to do with the combination of three parts which are inseparably connected to form a unitary needle having cer tain advantages as Will hereafter be noted.

Referring now to the drawing which illustrates one embodiment of my invention:

Figure 1 is a longitudinal section through the needle in its entirety; and

Fig. 2 is a transverse section, greatly enlarged, taken on line 2 2 of Fig. l.

The needle here shown is of the type Which is bent to present its top in an offset position, this being one of the common forms of needles now in use. My invention, however, is applicable not only to a needle having such a form, but to others as well so that unless otherwise specied, it should be understood that the precise form of the needle, from end to end, is not an essential feature.

The present needle is tubular in that it comprises a Wire core C of stainless steel, or the like, extending continuously from end to end with a tip 5 of suitable material, such as an osmium alloy, welded to its acting end. As shown, the upper needle portion 'I is straight, then bent at 8 to continue on obliquely through a middle straight portion 9, and near its tip is reversely bent at I to join with a lower straight portion I l adjacent which the tip is located.

This needle core is surrounded practically from end to end by a sleeve S of duraluminum or the like. This sleeve which is closely fitted to the core is locked thereto by the two bends 8 and I0. An outer tube T is also fitted closely over the sleeve throughout the upper straight end portion 'I of the needle. At one side, as at l5, this tube may be flattened to assist in its retention and rotative alignment within a suitable pick-up device.

The stainless steel core which I use for the present needle is of rather small diameter, .020" being suggested for the purpose. A needle so small can hardly perform satisfactorily unless reenforced, and this is one of the reasons why I apply the surrounding sleeve S which extends substantially for the entire length of the needle. The wall thickness of the sleeve need not be more than .007. As above noted, the sleeve is desirably made ci duraluminum, which is a light and relatively soft metal. When closely tted to the core, as a shea-th therefor, it acts as a vibration damper. I accordingly provide by the sleeve a means which tends to eliminate the scratching sounds which are commonly produced by friction of the needle tip on the record. The combined weight of the core and sleeve need be no greater, in fact may be less, than in the case of an ordinary one-piece needle of steel-an important factor in securing accurate response fidelity.

The tube 'I which is tted around the sleeve in the upper portion of the needle need not extend down beyond the bend 8. A suggestive wall thickness for the tube is .0135. The lower needle end is accordingly kept light in weight so as to have freedom for flexing, as required during play.

In the manufacture of this three-piece needle, there may be initially a very slight clearance of perhaps .001 between the core and the sleeve, and about the same clearance between the sleeve and the tube, but this is insufficient to permit any appreciable flexing or vibration between these parts. However, in the process of manufacturing, the core with the sleeve and tube applied in place, and before bending, may be subjected to a circumferential pressure from dies whereby to eliminate any remaining space therebetween.

A needle which is produced in accordance with my invention has a lighter weight, resulting in a lower mass. A wider frequency response is accordingly attained. It is also endowed with a flexibility or resiliency in a vertical plane as well as in a horizontal plane. The latter tends to reduce record wear, and the former also is saving on the wear of records since there is a certain amount of up and down motion due to tracking in the record groove. Should the needle be dropped, its ability to yield will offset to some extent the shock which otherwise might be darnaging, particularly to the tip.

In use, it will be found that the present needle will not vibrate beyond a. frequency of 3,000 or so, because at this point the vibrations are absorbed and will not reproduce noises developed in the higher frequency range.

I claim:

l. A phonograph needle comprising an elongated core of wire, a record-engaging tip secured to the lower end of the core and of a diameter at the juncture approximately that of the core, a circumferentially continuous sleeve closely surrounding the core for substantially the full length thereof and terminating at its lower endl at the juncture of the core and tip and maintained out of Contact with a record by said tip when the needle is in use, the core and sleeve being bent at spaced points lengthwise of the needle whereby to provide three straight portions with intervening bends forming a double lock to prevent relative endwise movement between the core and sleeve, and a tube closely surrounding the sleeve in its straight upper end portion commencing with the bend proximate thereto. and the core being solid from end to end with a diameter of the order of .020.

2. A phonograph needle comprising an elongated core of wire, a record-engaging tip secured to the lower end of the core and of a diameter at the juncture approximately that of the core, a circumferentially continuous sleeve closely surrounding the core for substantially the full length thereof and terminating at its lower end at the juncture of the core and tip and maintained out of contact with a record by said tip when the needle is in use, the core and sleeve being bent at a point lengthwise of the needle whereby to provide plural straight portions with an intervening bend forming `a lock to prevent relative endwise movement between the core and sleeve, and a tube closely surrounding the sleeve in its 4 straight upper end portion, and the core being solid from end to end with a, diameter of the order of .020.

MELVILLE A. MILLER.

REFERENCES oI'rED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date D. 135,953 Williamson July 6, 1943 1,246,694 Wood Nov. 13, 1917 1,619,863 Haase Mar. 8, 1927 1,768,704 McCarter July 1, 1930 FOREIGN PATENTS Number Country Date 814,894 France July 1, 1937

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