Electrical Socket Contact

This invention relates to an electrical contact, and more particularly pertains to a multi-sided blade contact receivable in a connector receptacle adapted to receive a metal pin contact of a connector plug. The contact engagement establishes electrical communication between conductors terminated in the contacts of mating connectors. Although the use of receptacle-like, multi-sided contacts is known in the art, the provided blade contacts of this invention provide advantages not present in similar type contacts of the prior art.

Thus, four-sided contacts defining an open ended receptacle have been employed in the prior art, being disposed in square openings of connector receptacle insulators. The bladed contacts of the prior art are formed from integral blanks, and each blade or wall thereof is uniformly necked in or bent inwardly toward the central axis of the enclosure so as to define a reduced throat area. The enclosure open end is of adequate sectional area to receive a projecting pin of a connector plug. The necked-in throat area is of such reduced sectional area as to effect a gripping action on the pin periphery inserted through the throat. To enable the blades to be uniformly inwardly bent at the throat area without interfering with one another, the widths thereof were reduced at the throat areas which define the contact area of maximum stress. The dimensional reduction proportionately reduces the pin-gripping forces exerted by the contact blades or walls on the engaged plug pin.

In accordance with the contact of the provided invention a novel multi-sided contact is provided in which the contact walls defining a pin-receiving enclosure are formed from a slotted integral blank as with the prior art. However the blank walls are performed so as to be slightly off-center relative to the central axis of the enclosure formed thereby following a blank-bending step. As a result, each wall may be of its full width where bent inwardly at a central portion to define a pin-engaging throat section. Also, simultaneously with formation of the throat, an open contact end is formed by outwardly flaring wall portions to desired angles. Thus when inserting such contact in a receiving aperture of a connector receptacle insulator, the flared contact ends effect a preload in the contact throat area providing gripping action of desired force on the plug pin received therein.

Thus it is an object of this invention to provide an electrical contact particularly adapted to engage a plug pin with gripping force of desired magnitude. The regulatable gripping force is made possible by virtue of flared ends extending from a pin-engaging throat area formed in each contact.

It is a further object of this invention to provide a novel contact for an electrical connector particularly adapted to engage a mating connector pin in which the walls of such contact defining a pin-receiving receptacle are disposed in off-center relationship with respect to the longitudinal axis of the pin-receiving opening of such contact receptacle. Such relationship enables the full width of the blade walls to be utilized in the area of pin engagement.

It is yet another object of this invention to provide a novel end construction for a contact formed of a plurality of flared wall portions which, upon converging into interengaging relationship, coact to define a rigid periphery about an insulator contact-receiving periphery. Such a novel wall interlock prevents inadvertent positioning of a plug pin behind one of the walls of the contact and an adjacent insulator surface, and thus assures proper reception of a plug pin within the contact.

It is another object of this invention to provide a novel contact for use in electrical connectors in which a double bend is present in each blade-wall portion of such contact adjacent the contact throat area adapted to engage a plug pin. The double bend limits the outward movement of each contact wall or blade if a pin is inserted and tilted while engaged with such contact.

It is yet another object of this invention to provide a simplified method for forming a contact for use in an electrical connector, the contact being readily formed by means of a simple stamping or punching operation followed by a simple bending operation. The bending operation imparts to such contacts the desired pin gripping force when placed in an insulator cavity.

The above and other objects of this invention will become more apparent from the following detailed discussion when read in the light of the accompanying drawings and appended claims.

In one embodiment of the provided invention a contact blank is provided comprising a metal sheet having a plurality of parallel longitudinal slots. The blank may comprise a phosphorous bronze metal sheet of approximately six mils thickness. The slots extend normally from a planar, unapertured transverse band portion and serve to define a plurality of parallel strips or blades which will in turn serve as walls of a box-like receptacle for engaging a contact pin of an electrical connector plug after the blank is predeterminately bent. The blades are arranged in a novel off-center relationship with respect to the central longitudinal axis of a contact-receiving enclosure formed when the transverse band from which the blades extend is bent along axes extending through said formed slots. The blades are also bent along a common transverse axis transversely disposed to the longitudinal axes of the contact strips. Thus, when the blank and transverse band is folded along such axes extending through the blank slots, the four blades or contact walls are disposed in off-center relationship with the central axis of the opening defined by the walls. The end of each of the blades or contact walls diverges from the transverse bent portions so as to provide a flared opening oppositely disposed to a square, box-like portion formed when the transverse blank portion is folded.

Thus, in accordance with the provided invention, the blade-forming slots are formed in the blank so that when folding the blank along axes disposed in the solid transverse band portion, each blade wall is in off-set relationship with respect to the longitudinal axis of the receptacle opening defined by the blades or walls. As a result, a maximum width of material may be retained for each blade when folded in along the throat area for desired gripping action with a plug pin received therein as will hereinafter be explained in greater detail.

By desired angular disposition of the flared end portions of the contact blade walls, the blades may be preloaded when the contact is inserted in a contact-receiving insulator opening. The distal portions of the contact not only effect a gripping action with the insulator, but in addition provide a desired action at the throat area where the four contact walls mutually engage.

For a more complete understanding of this invention reference will now be made to the drawings wherein:

FIG. 1 is a perspective view of a contact made in accordance with the teachings of this invention;

FIG. 2 is a side elevational view of the contact of FIG. 1;

FIG. 3 is an end elevational view taken on line 3--3 of FIG. 2;

FIG. 4 is a plan view of a blank from which the contact of FIGS. 1, 2, 3 is formed;

FIG. 5 is an elevational view of a contact made in accordance with this invention after reception in a contact-receiving opening of an insulator fragmentarily illustrated in FIG. 5 in section and employing a solderless wire-termination system;

FIG. 6 is an end elevational view taken along line 6--6 of FIG. 5;

FIG. 7 is a perspective view of a plastic-body electrical contactor utilizing the contacts of FIGS. 1 through 5;

FIG. 8 is a view similar to FIG. 7 illustrating an electrical connector utilizing the contacts of this invention and employing a metal shell.

Referring now more particularly to FIG. 1 a contact 10 is therein illustrated comprising conductor-terminating portion 12 and a pin-engaging contact portion 14. The contact 10 thus comprises an integral unit adapted to engage a conductor or wire by means of portion 12 and a portion 14 adapted to releasably engage by means of a bayonet-type engagement, a metal contact pin of an electrical connector plug. The invention hereinafter described is concerned with contact portion 14; portion 12 of the contact 10 may be of any structure adapted to engage a conductor in electrical engagement, such as the solderless termination system disclosed in McKee U.S. Pat. No. 4,035,049, illustrated in detail in FIG. 5 of the drawing. The wire or conductor-termination portion 12 of the contact 10 may also comprise any of well-known solder pot, crimp snap-in contact termination systems well-known in the art.

The contact 10 is formed from a blank 16, see FIG. 4, which has been stamped so as to form parallel longitudinal slots 18. Blank 16 is formed of a metal of good electrical conductivity such as a phosphorus-bronze alloy. The slots in turn define four parallel longitudinal blade or contact side portions 20. The four contact blades are contiguous and integrally formed with a solid transverse band portion 22. The blank transverse band portion 22 is also integrally formed with a connecting neck 24 so as to be integrally formed with blank portion 12B from which the contact termination portion 12 of FIG. 1 is formed following bending along the longitudinal axes 26.

In accordance with this invention, slots 18 are stamped out or otherwise formed in blank 16. Such slots are formed in such a manner that when blank 16 is folded along the bend axes 26 disposed in blank portion 12 and portion 22, the central longitudinal axes of walls or blades 20 will be in offset relationship with the central longitudinal axis of the pin-receiving enclosure 30, see FIG. 1, formed by the blade walls 20; the off-center relationship is apparent from end views comprising FIGS. 3 and 6 of the drawing.

Thus, the provided contact differs from the prior art contacts of this type possessing contact blade walls uniformly arranged about the longitudinal axis of the pin-receiving aperture defined by such contact walls. After bending the contact-forming blank in accordance with this invention, by virtue of the offset relationship of the blade walls, after each of the blade walls has been transversely bend along a transverse bend axis 32 so as to form the S-shaped reverse bend portion 34 more clearly seen in FIG. 1 of the drawing, flared end portions 36 of the contact 10 are simultaneously formed as is also apparent from FIG. 1 of the drawing.

By predetermined design of the reverse bend 34 of each of the blade walls 20, the angular disposition of the flared end portions 36 of the contact is determined. The greater the blade or wall divergence from bend 34, the greater the loading of the throat receiving a contact pin in the normal position of contact use. Flared portions 36 will be urged to converge when the contact 10 is inserted in a square insulation contact cavity such as cavity 38 of electrical connector insulator 40 illustrated in FIG. 5.

Laterally and inwardly projecting from each blank blade 20 is a bent ear 42, seen most clearly in FIG. 3. It is the function of these bent ear portions integrally formed with each contact flared blade portion 36 to serve as a stop for an adjacent blade portion 36, preventing the inward movement of each contact blade portion beyond a minimum periphery. As a result of each ear portion serving as a stop for an adjacent contact flared wall portion, the pin-receiving or entrance end of each contact 10 will appear as seen in FIG. 6 of the drawing. These peripheries may be sized slightly larger than that of the receiving insulator.

Thus upon insertion of each box contact 10 formed from blank 16 illustrated in FIG. 4, in an insulator contact cavity, the flared end portions of the blank 16 are converged by the walls of the cavity, each blade flexing inwardly until innermost blade portion 35 thereof engages an edge of an adjacent blade at reverse bend 34 in the manner illustrated in FIG. 6 of the drawing. Such bending of the blade flared ends as the contact blank is inserted within the insulator opening will provide a preload at the contact throat or pin-engaging periphery as above explained. The throat defined by innermost projecting portions 35 of each blade bend 34 is seen most clearly in FIG. 6 of the drawing. The throat is employed for gripping peripheral portions of a contact pin inserted therein such as contact pin 46 illustrated in FIG. 5. Thus in the course of inserting contact 10 in a connector insulator opening, flared blade portions 36 will transform from the appearance of FIG. 3 to that of FIG. 6.

By virtue of the fact that the flared contact wall portions 36 may not move inwardly beyond the position illustrated in FIG. 6, it is impossible for a pin such as pin 46 seen in FIG. 5 to enter behind one of the flared end portions of the contact as the bent blade portions 42 function as stops preventing the four flared blade portions 36 from moving away from the insulator walls.

The prior art contacts necessitated a reduction in contact wall width at the bent, throat-defining portions of the contact walls which would engage an electrical plug pin to prevent mutual interference. Such reduction in width is not necessary with the contact of the provided invention by virtue of the offset relationship of the blades or walls relative to the central longitudinal axis of the receiving aperture 30. As a result, a greater blade width may be retained for stronger, more effective pin-gripping action, and a more secure contact is assured when a plug pin is received in the contact opening at the throat defined by bends 35.

It should also be noted that the double bend at 34 of each contact blade 20 creates not only throat bend 35 but also adjacent, outwardly directed bend 37 seen in FIGS. 2 and 5. Bends 37 minimize over-flexing of a contact wall if a pin such as pin 46 of FIG. 5 is tilted while engaged with the contact 10. The contact blade or wall will flex in the course of such pin pivotal movement until the contact portion bears against the contact cavity wall. The reverse bend portion 37, therefore, reduces the possible wall bending action in the provided contact construction in the course of pin engagement. As a result the danger of the contact 10 assuming a "set" which results in impaired engagement with a pin such as pin 46 of FIG. 5 is minimized.

The provided contacts may be employed in any electrical connector employing box-like contacts of this type including those sold by TRW Inc. of Elk Grove Village, Illinois under the name Cinch D Subminiature Connectors. Thus connector 44 of FIG. 8 illustrates such a D Subminiature Connector employing the contacts of this invention surrounded by metal shell 49. Shell 49 may be of cadmium plated steel and insulator 51 may be formed of an appropriate dielectric such as nylon or diallyl phthalate. The shell is keystone-shaped to polarize conductors in the course of intermating.

Connector 50 of FIG. 7 utilizes an all plastic insulator body which may be of glass-filled polyester or other appropriate plastic in which the metal contacts 10 are mounted. It will be noted from FIG. 7 that such connector 50 may have integrally formed therewith, a plastic latch portion 52 which may, in turn, have a longitudinal opening 54 therein for passage of a screw member in the event that such a screw is desired for engagement purposes with either a mating connector, a hood or a chassis. Latch portion 52 may serve a similar function for latching the illustrated connector 50 to another electrical component mounting component or protective component such as a hood or the like.

As above pointed out the termination portion of the contact 10 may be of a variety of types. By way of illustration, FIG. 5 depicts a solderless termination system of the type disclosed in McKee U.S. Pat. No. 4,035,049 which contact portion 12M may comprise downwardly disposed strain relief tabs 56, folded-over jaw portions 58 adapted to cut through the insulation of a wire to be terminated and locking tab 60 adapted to serve as a means for retaining the contact 10 to insulator 40.

It is believed apparent from the foregoing that the provided contact enables a desired gripping force to be exerted in an engaged pin by desired initial angular disposition of the blade flared portions 36 prior to insertion in an insulator cavity. The novel offset arrangement of applicant's contact walls enables the full wall widths to be retained without narrowing at the throat area. Accordingly, desired contact strength is assured. The novel blade tabs assure a fixed distal contact periphery adjacent the insulator opening periphery and prevents a plug pin from inadvertently being inserted between the insulator cavity wall and an outside blade surface.

Although the foregoing description has been specific with respect to contact 10 having four sides, it is believed apparent that the foregoing structural features are applicable as well to contacts having three or more sides.

The above-discussed contact construction possesses many structural features providing functional advantages as above brought out in detail. The illustrated contacts have been presented by way of example only. This invention, therefore, is to be limited only by the scope of the appended claims.