Self-shorting phono plug

Hi] 3,600,531

United States Patent ,[72] Inventor OttoHoegerl

Saegertown, Pa.

[21] Appl.No. 35,830

[22] Filed May 8,1970

[45] Patented Aug. 17,1971

[73] Assignee National Tel-Tronics Corporation

Yonkers, N.Y.

[56] References Cited

UNITED STATES PATENTS

3,045,079 7/1962 Frantz etal................... 200/51.1

3,387,104 6/1968 Friend.......................... 200/51.1

Primary Examiner— Stephen J. Novosad Assistant Examiner— Lawrence J. Staab Attorney—Charles E. Temko

[54] SELF-SHORTING PHONO PLUG 2 Claims, 4 Drawing Figs.

[52] U.S.C1........................................................ 200/51.1,

339/177 E

[51] Int. Cl.........................................................HOlr 33/30

[50] Field of Search...................... 339/19,

182, 183,177; 200/51.09, 51.1; 179/96

ABSTRACT: A self-shorting plug for use in connection with a phonojack including a conventionally configured centrally disposed prong, a surrounding outer body member, and a flat steel shorting spring staked at one end thereof to the border of a centrally disposed opening in said outer body member, and having a free end terminal penetrating a slotted opening in a skirt portion of said outer body member to contact a surface of said prong.

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PATENTED AUG I 71971

3.600,531

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3,600,531 ¹ . 2

SELF-SHORTING PHONO PLUG

This invention relates generally to the field of electronic hardware, and more particularly to an improved self-shorting phonoplug of a type used to interconnect a phonograph head ⁵to an amplifier or similar structure. Devices of this general type are well known in the art, and the invention lies in specific constructional details.

Phonoplugs are characterized in the provision of a centrally disposed prong surrounded by a cylindrical main body ^1Cmember, one end of which is provided with a resiliently expandable skirt which engages the outer surface of a corresponding jack, while the centrally disposed prong penetrates a corresponding opening in the jack. The prong and body member are mutually electrically insulated by a planar fiber ¹⁵washer, and an opening in the body member permits communication of a conductor with the inner end of the prong.

For some installations, it is desired to use a self-shorting plug, in which means is provided for electrical interconnection ₂o between the body member and the prong when the plug, is in disengaged position with respect to the corresponding jack. This is accomplished by means of a spring formed of wire, one end of which is secured about the centrally disposed opening in the body member, and another end of which penetrates one 25 of the slots in the resilient skirt on the body member to contact an outer surface of the prong adjacent an inner end thereof! This spring is moved out of the way when the plug is inserted within a jack, and then contacts the outer cylindrical surface of the jack to assist in completing the circuit. In prior art con- 30 structions, the spring is formed of piano wire, suitably plated, and is relatively fragile, to be easily damaged by manual handling, particularly when considerable force must be applied to the device at the time of interconnection or disconnection with a jack. Because of the delicate construction, dif- 35 ficulty has been encountered in maintaining positive contact. Further, the spring has been difficult to manufacture to a uniform standard, and as a result, the variance in resiliency has been excessive. A further disadvantage has been the tendency for the staking of the spring at the fixed end thereof to ⁴⁰loosen, owing to the difficulty in obtaining proper purchase upon narrow gauge wire, so that the terminal becomes misaligned with the slot in the outer body member, and is unable to make proper contact.

It is therefore among the principal objects of the present in- ⁴³vention to provide an improved self-shorting phonoplug of the class described, in which the above mentioned disadvantages have been substantially eliminated.

Another object of the invention lies in the provision of an improved shorting spring which may be readily incorporated into existing phonoplug constructions without modification of the latter.

Yet another object of the invention lies in the provision of an improved self-shorting phonoplug of the class described, in ₅₅which the cost of manufacture may be of a reasonably low order, directly comparable with existing prior art constructions, thereby permitting consequent wide sale, distribution and use.

Yet another object of the invention lies in the provision of a gq Shorting spring for use in conjunction with phonoplugs which may be formed as a metallic stamping with improved shaperetaining properties.

These objects, as well as other incidental ends and advantages, will more fully appear in the progress of the follow- 65 ing disclosure, and be pointed out in the appended claims.

In the drawing, to which reference will be made in the specification, similar reference characters have been employed to designate corresponding parts throughout the several views. 70

FIG. 1 is a side elevational view, partly broken away in section of an embodiment of the invention.

FIG. 2 is a side elevational view of the shorting spring forming a part of the embodiment.

FIG. 3 is a bottom plan view of the shorting spring. 75

FIG. 4 is a view in elevation of a stamped blank from which the shorting spring is formed.

In accordance with the invention, the device, generally indicated by reference character 10, comprises broadly: an elongated axially disposed prong 11, an insulating member 12, an outer body member 13, and a shorting spring 14.

The prong 11 may be of entirely conventional construction, including an outer end 17 which is preferably rounded to facilitate insertion into a jack (not shown), and an inner end 18 defining first and second flanges 19 and 20, respectively, for engagement with the insulating member 12.

The insulating member .12 is preferably of planar fibrous material, having a central opening 23 disposed between the flanges 19 and 20, and a peripheral edge 24 corresponding in diameter to the inner diameter of the outer body member 13.

The outer body member 13 is preferably formed as the product of a metallic drawing operation, and includes a slotted skirt 27, the inner surface 28 of which makes contact with the outer surface of a jack in well-known manner. The skirt 27 is interconnected by a tapered portion 29 to an upper cup portion 30 having an upper wall 31 forming a central opening 32 bounded by a beaded edge 33, as is known in the art.

The shorting spring 14 is preferably formed as a metallic stamping indicated by reference character 34 in FIG. 4, and includes a first end 35 having a hole 36 defining edge segments 37 which are preferably corrugated to permit convenient staking. A tapered portion 38 communicates with a second end 39 having a laterally extending tab 40.

Referring to FIGS. 2 and 3 in the drawing, the spring is shaped to provide a planar mounting portion 42, interconnecting with an arcuate portion 43, in turn leading to a longitudinally disposed planar portion 44. The tab 40 is bent with respect to the plane of the portion 44 to form a terminal indicated by reference character 45.

The device is assembled in well-known manner, in which the insulating member 12 is first affixed to the prong 11, and subsequently forced within the outer body member 13. The spring 14 is attached thereto by staking over the edges of the central opening 32 upon the edges 37 of the hole 36 after aligning the terminal 45 to project through one of the slots in the skirt 27.

As will be understood from a consideration of FIG. 1, the resiliency of the spring 14 is such that when the device 10 is disengaged with respect to a jack, the terminal will contact the outer surface of the prong 11. Upon engagement with a jack, the rounded edge 46 of the terminal 45 will serve as a camming surface to urge the same radially outwardly, to permit full engagement of the plug with respect to the jack, and allow the edge to rest on the outer surface of the jack to assist in completing an electrical communication therethrough. Upon withdrawal of the plug, the spring will return to its relatively unstressed condition, providing an immediate short.

It is to be understood that it is not considered that the invention lies within the specific details of structure shown and set forth in this specification, for obvious modifications will occur to those skilled in the art to which the invention pertains.