US 3208030 A
Description (OCR text may contain errors)
p 1965 R. T. EVANS ETAL 3,208,030
ELECTRICAL CONNECTOR Filed Dec. 6, 1962 2 Sheets-Sheet 1 FIG. I
INVENTORS ROBERT I EVANS EDWARD C UBERBACHER ATTORNEY Sept- 1965 R. T. EVANS ETAL ELECTRICAL CONNECTOR 2 Sheets-Sheet 2 Filed Dec. 6, 1962 United States Patent 3,208,039 ELECTRTCAL CONNECTOR Robert T. Evans, Yonkers, and Edward C. Uberbacher,
Poughkeepsie, N311, assignors to international Business Machines Corporation, New York, N51! a corporation or" New York Filed Dec. 6, 1962, Ser. l o. 242,728 9 Claims. (Cl. 339-47) This invention relates to electrical connectors and to contact elements for electrical connectors.
An object of this invention is to provide an electrical connector composed of two connector members having contact members therein which are adapted to be connected to the ends of component leads, separate wires or wires of a cable, such connector members being matable and similar to each other in shape and size whereby any connector member may serve either as a plug or as a receptacle.
Another object of the invention is the provision of an improved electrical contact element adapted to be mounted in a connector member and adapted to provide an economical, effective and efficient electrical connection with a contact element of another connector member, said contact elements being similar to each other in design, construction and assembly.
A further object is the provision of a contact element of the kind noted and adapted to be connected to the end of a conductor wire and then inserted, with the wire connected, into the body of a connector member, the contact element having multiple latching means for holding it in all directions. However, the latching means is designed with flexible stop extensions subject to manipulation for outside release to permit removal of the contact element from either the front or rear of the connector member.
Another object of the invention is the provision of an economical form of contact formed with both male and female elements of contact so that a connector comprising such contacts is of the interchangeable hermaphroditic type. The sheet metal contact is formed with both plug and socket features in addition to wire and cable securing means. The continuous serpent form of the contact provides a plurality of points of contact when a pair is brought into wiping engagement.
An object of this invention is to provide insulated electrical connector members and formed sheet metal contact elements therefor of the above mentioned character which are relatively simple, economical and easy to manufacture and assemble and still are rugged in construction and reliable in operation. A bellows formation of the contact adds to the flexibility of it and also provides two extensions to be engaged by two opposite extensions so that between them there is a double pinching and wiping action for each pair of interengaged contacts. Attachment of a wire to a contact is optionally by crimping, soldering or welding.
An important object of the invention is the design and proportioning of a contact element with small functional area to save on the cost of plating. Since gold plating comprises a large part of the cost of low voltage contacts, an important saving is effected by the present design. The contact element is of miniature size and the functional contact areas are kept small and isolated or raised so that resist material may be coated on most of the contact element when it is being partially plated, and therefore the selective plating of gold is limited to the small functional surfaces.
The invention is notably useful when embodied in an electrical connector having a plurality of contact elements for closing a multiplicity of electrical circuits. The connector members are adapted to be formed in any size or from a plurality of grouped structural units permitting a large number of contact elements to be assembled easily for constituting a connector member.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawing.
In the drawing:
FIG. 1 is a perspective view of a form of contact element of the present invention.
FIG. 2 is a sectional elevation View of a pair of novel connector members containing the novel contact elements.
FIG. 3 is a detail perspective view of the opening or inner chamber of an insulation connector body which is designed to receive and hold a contact element.
FIG. 4 is a sectional elevation view taken along line 44 in FIG. 2 and showing the wiping surfaces of contacts as connected.
FIG. 5 is a perspective view of another variety or embodiment of the type of contact element shown in FIG. 1.
A main object of the invention is to provide a better interchangeable form of multiple electrical connector in which the contacts make a better electrical connection, are more easily inserted and removed for assembly and replacement, require less force for mating, and in addition are economical in construction. All this is accomplished by the novel formation of a common insulation block and a universal form of contact design wherein the contact is one thin flexible strip of metal formed with a stiffened center portion as a base for three kinds of extensions: stop extensions, mating extensions, and wire securing extensions. The stop extensions are oppositely facing to hold an inserted contact in the insulation block in both directions and, furthermore, such stops are flexible and suited for manipulation from the outside of the block so that a contact may be inserted or withdrawn in either direction. The mating extensions are each formed with several serpentine folds, bellows style-the first two folds being brought close together while a third outer fold is brought out with a wide radius to extend flexibly over the other folds and superimpose a curved tip over the bent end of the other folds, whereby interengagement of blocks and two sets of extensions effects a double pinching and wiping engagement because the two contacting inner folds are pinched between the curved tips of the two outer folds to effect a very reliable form of dual electrical contact for each mating point. The wire securing sections serve to clamp the insulation and wire portions of a conductor to the contact end to act as a strain relief retainer for a solder or weld connection of the wire to the contact. Each universal insulation block is formed with a plurality of contact receiving openings, each opening having an inner stop shoulder terminating a ramp formed on the floor of the opening, and a rabbet formed alongside one inner corner of the opening wherein a contact edge may be confined to securely hold the entire contact member, said opening and said rabbet extending all the way through said block, whereby a contact may be inserted or withdrawn in either direction through said opening.
Referring to the drawing in greater detail, there is shown an electrical connector of this invention comprising two connector members which are designated, generally, by the reference numbers 20 and 21, respectively. The two connector members 20 and 21 of the illustrated embodiment are substantially identical to each other in their details of construction and are adapted to be interengaged, as shown in FIG. 2 of the drawing, for interconnecting a contact element or terminal 22 of member 20 with a similar contact 23 of member 21. Each of the contact elements is adapted to be separately connected (as explained hereinafter) to the ends of conductors 24, whereby the electrical connector serves to join the conductors of one connector member to the conductors, respectively, of the other connector member.
Each connector member comprises a body or block or 21 formed of non-conducting material. Although any plastic material such as a synthetic polymer, e.g., nylon, is a preferred material from which to form the block, other insulation materials as ceramics and harder non-conductors are usable. A full block 20 or 21 is either square or rectangular in outer form and provided with one or more openings or holes 25, each hole designed to receive and hold a contact element 22 or 23. The holes 25 are usually arranged in regularly spaced rows and columns for multicontact connectors, but one pair of coinciding holes 25 as shown in FIG. 2 is believed ample showing to illustrate the principles of the invention.
FIG. 3 shows how the inside of the openings 25 is formed to facilitate the insertion of a contact element, the retention of the element and the mating of two such elements. A wide opening floor area 26 is joined to a sloping ramp area 27 which has constricted side shoulders 28 as inner ends of flared opening with one wing 29 coinciding with the wide floor area 26. The sharp corner edge 30 of the hole opening is engaged by one contact tab or lug to hold the contact in place and blocked from movement to the right, while the edge 31 is engaged by a retainer finger on the contact to hold it from movement to the left. A slot, notch or rabbet 35 is formed along one side of hole 25 at the near side as seen in FIG. 3.
Referring to FIGS. 1 and 2 of the drawing, a contact element or terminal 22 is shown as formed from a single elongated flat strip of metal such as spring stock of copper alloy or Phosphor bronze. For ease of description the terminal strip may be described as comprising a contact engaging front end portion as bellows 36 terminating with an end spring leaf 37, a conductor-connecting rear end portion 38 terminating with an end pair of wings 39, and a middle portion 40 between said end portions.
A conductor retaining pair of sides 41 is formed by bending the side edges of the terminal strip toward each other to provide a well for solder or a confined spot wherein the end of the wire 42 may be welded onto the contact. This inner bend is continued to form the wings 39 which are to be crimped around the outside surface of an insulation jacket or coating 24 of the wire signal conductor 42. Thus a conductor wire is secured both mechanically and electrically in a strong fashion to the rear end of a contact 22.
An important aspect of the invention resides in the feature that the contact terminals are adapted to be connected to the ends of the conductors and then inserted into the blocks of the connector members, or retracted therefrom in either direction, and when once in such block they remain in position tightly and secure against being accidently loosened or withdrawn. For such securance, the middle portion 40 of the contact has a spring retainer or stop finger 45 struck from it leaving an opening 46 in the strip. The spring finger 45 extends longitudinally with respect to the strip contact 22 with that end of the finger which is remote from the conductor end portion of the strip, integral with the strip, while the other end of the finger is free. Thus the finger may be pressed toward or partially into its opening 46, as when the contact strip 22 is being inserted into the insulation block 20, and then the finger 45 will spring outwardly, when free of block hole restraint, to the position shown in FIG. 2, whereby the end of the finger engages the shoulder 31 formed on the inside of the block to prevent withdrawal of the terminal contact from the block in a direction to the left. In order to prevent displacement of the assembled contact terminal toward the right, it is provided with another stop extension in the form of an offset lug or tab 47 which is bent out of a rear extension of a side wall 48 formed on one side of middle portion 40 of contact strip 35. Tab 47 engages around the edge 31, FIG. 3, of the hole 25 in block 20 and is on the thin extension 49 which is flexible enough to permit manual forcing of the tab into the hole should it be desired to remove the left contact through the hole 25 toward the right, FIG. 2. For manual removal in the opposite direction of the same contact, FIG. 2 compression of finger 45 upward to free it from shoulder 31, frees the contact for removal toward the left. From the foregoing it is clear that a contact may be inserted into the block hole 25 from either side and locking parts 45 and 47 will snap into locking positions, but both said parts may be manipulated to permit retraction of the contact in either direction with or without a conductor attached.
The side wall formation 48 in rising from the flat midsection 40 of the contact, provides an L shaped crosssection which is a strong foundation for the spring leaf end of the contact. The upper edge of side wall 48 also forms a broad cooperating surface with the inside of block hole 25 just as the flat middle area 40 rests on the floor of the hole and the edge of area 40 fits into the rabbet or slot 35 to seat the contact firmly therein.
The contact engaging or wiping end of contact 35, FIG. 1, is narrower and more flexible than the middle portion 40 and it comprises a sort of bellows fold of strip with portions 50, 52 and 54 folded back and forth, portion 52 being the penultimate fold. Adjacent portions 50 and 52 are folded close together and at the bent end define a short raised platform over a narrow slot 51 which is allowed to remain open because a radius of small size (about equal to thickness of stock) is better than a sharp bend with respect to distributing the stresses at the bend of relatively hard spring stock. The outer pair of folded portions 52 and 54 are more widely spaced to define a relatively wide curved end 53 which is a flexible base for the upwardly flared outer spring leaf wiping blade 37. The spring bellows design of folded portion 40, 52, 54 provides a very flexible sort of wiping contact which readily accommodates itself to mating with a similar contact under adverse conditions of being receptive to any one of thousands of similar blocks which are not always identical in size or perfect in contact disposition.
The manner in which the contact terminals of c0nnector member 20 interengage or mate with respective contact terminals of connector member 21 appears best in FIG. 2. Referring in particular to the wiping contact areas of portions 50, 52 and 37 of contact 22 at the left in block 20 as duplicating those of FIG. 1, and a similar contact in block 21, these being in alignment for interengagement and being inverted with respect to each other, it will be noted that the fold 50, 52 of the left contact fits between the fold 52, 54 of the right contact and the same condition is duplicated with regard to the other pair of folds. Therefore, a novel form of double pinching and wiping engagement is effected between joined contacts. The sectional view, FIG. 4, illustrates how there are three lines of wiping contact between terminals 22 and 23 when forced together. This wiping area, encircled as 55 in FIG. 1, is comparatively small and near the contact ends and thus accessible and limited to use of small amounts of precious metal plating to gain economical use of such costly coatings.
The normal spacing between the middle bellows fold 52 and the contact leaf 37 is smaller than the end thickness of 50, 52 so that when the contacts are mated there is flexure of the leaf 37 and pressure during wiping engagement and thereafter as the contacts remain connected.
Blocks 20 and 21 may have holders or shrouds (not shown) which also act as assembly guides to lead the contact fold 50, 52 into the opening 37, 52 of the other contact. However, since the contact ends extend, in the case of only one or a few mating points, the contacts may be brought together without mechanical guidance.
An alternative form of the contact or terminal 22 is shown in FIG. 5. There it is seen that many features such as the bellows of a fold 61 comprising contact portions 60, 61 and 64 are the same as the other contact. However, the midportion is stiffened further by the addition of an extra side wall so that one side wall portion 66 is plain and the other wall 65 is formed with a flexible extension 68 which is formed with a bent lug or tab 67 which acts as a movable stop similar to stop 47. The wing ends 69 for grasping conductor '24 are simple in form because the wire 42 has its end welded, soldered or secured directly to the bent area 70 which is a broad and relatively immovable area of the contact leaf 64. Also present is a stop finger 75 similar to finger 45.
It is obvious that the contact terminal of FIG. 5 will fit into an opening 25 of a block such as blocks 20, 21 without the need for rabbet or slot 35 and there serve in all ways like the contacts described hereinbefore. The block opening 25 may be symmetrical in the case of the use of the contact of FIG. 5, i.e., the flared wing 29 is to be duplicated on the near side of the opening when slot 35 is omitted.
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made the-rein without departing from the spirit and scope of the invention.
What is claimed is:
1. A contact comprising a single strip of thin flexible metal having,
an L shaped stiffened midsection,
a pair of opposite stop extensions formed to extend from said stiffened midsection,
a reduced width portion at one end of said contact, said portion being formed with a plurality of folds, bellows style, and a final fold extending as a contact leaf, said folds being proportioned and arranged to receive the folds of a similarly shaped contact for mating electrical engagement,
and a conductor clamping portion on the other end of said contact.
2. A contact of the kind set forth in claim 1 wherein,
one of said stop extensions is a flexible reduced portion extension of the side wall of the L shaped midsection,
and the other stop extension is a finger struck down out of the base of the L shaped midsection.
3. A contact of the kind set forth in claim 1 wherein,
said reduced width portion has a first fold, sharply bent to lie against the base of the L shaped midsection except for a slightly raised portion near the fold bend,
and a second fold with a comparatively large radius rbend out of the first fold to form a free contact leaf coextensive with said first fold, said leaf having a curved end opposite said raised portion for limited area wiping contact reception of an inserted contact.
4. A connector block of insulation material,
a contact receiving formation in said block formed around an opening in said block comprising,
a shoulder terminating a sloping ramp formed on the floor of said opening,
a flared entry into a reduced width wall for said ramp, and
a full length rabbet formed alongside one edge of said opening wherein a contact edge may be confined,
whereby an L shaped contact may be fitted into and tightly held in said Opening and rabbet with the outer sides of the L shaped contact confined by the opening walls and the one edge of the L shaped contact confined in said rabbet, both said opening and said rabbet extending through said block from one outer face to another outer face, whereby a contact may 6 be inserted or withdrawn in either direction through said opening.
5. A contact of a single formed strip of thin flexible metal comprising:
a U shaped midsection,
a pair of opposing stop extensions formed on said midsection,
an elongated reduced width portion at one end of said I contact, said reduced portion being formed as a plurality of flat folds, bellows style, the first two folds I being bent at a small radius which is about equal to .the thickness of said strip, said folds forming a slightly separated portion as a short raised platform near the bend, and beyond the platform .said folds are folded close together with the second fold separating with a wide radius into the final fold, said final fold extending as a .free contact leaf with a curved end opposite said platform, and
a conductor clamping portion formed on the other end end of said contact.
'6. A contact terminal for an electrical connector which comprises,
a thin contact element having front, middle and rear ,portions,
means on said rear portion for engaging an electrical conductor,
said middle portion being formed as a relatively stiif L I shaped section,
flexible stops formed on said middle portion for contact retention in two directions when in a holder but flexibly disengageable by manipulation for retraction of said contact from such a holder in either direction,
said front portion is stock bent as a bellows of three folds including a pair of contact leaf extensions, one relatively stiff formation of folded layers and the other of a singular curved free end formation,
whereby said leaf extensions are interengageable in overlying position with respective extensions of a similarly constructed contact terminal, with said free end formations of each contact resting on a folded extension of the other contact with said folded extension pinched between the pair of extensions of the other contact.
7. -An electrical connector member comprising,
a body of non-conducting material having an opening extending therethrough,
a thin angular bent con-tact element disposed in said opening,
said contact element having front, middle and rear portrons,
means on said rear portion for engaging an electrical conductor,
said middle portion being stiffened with one or more angular bent edges,
said front portion including a pair of contact leaf extensions, one with a straight end and the other with a curved lead-in end,
whereby said leaves are interengageable in reverse overlying positions with respective leaves of a similarly designed contact element, with the straight ends overlapping and in contact and the curved end of each element pressing on the straight end of the other element in double pinching engagement.
8. An electrical connector comprising:
a connector .block of insulation material having a con tact receiving formation formed around the walls of an opening therein where there is,
a stop shoulder terminating a sloping ramp formed on the floor of said opening,
a flared entry into a reduced width wall for said ramp, a full length notch formed alongside one inner wall of said opening to receive an edge of a contact, both said opening and said notch extending through 7 said block from one outer face to another outer face, a contact fitted inside said opening and notch, said contact being a single strip of thin flexible metal strip, said folds near the bend forming a slightly separated portion as a short raised platform, and beyond the platform said folds are folded close together, with the penultimate fold separating from having an L shaped stiff midsection and an extend- 5 the association with a wide radius into the final fold, r ing contact portion, and l said final fold extending as a free contact leaf with a P of pp p extensions formed 011 said a curved end opposite to said platform, whereby section to cooperate with the face and stop shoulder of similar pairs of platforms and curved ends of two Said block, one Of Said p extensions being a flexible identical contacts may be interen-gaged and establish reduced portion extension of the side wall of the 10 mated Wiping Contact L shaped midsection, and the other stop extension being a flexible finger struck down out of the base References Cit d by the Examiner of the L shaped midsection, said extension flexure permining manipulation, UNITED STATES PATENTS whereby said contact may be inserted or withdrawn in 5 2,486,235 10/ 49 Hurst X either direction through said opening. 2,539,230 1/ 1 C g 339*278 X 9. An electrical contact formed to provide electrical 2,882,512 4/59 Morone 339--193 connection with a similar contact when in mating holders 2,891,103 6/59 Swengel 339-426 X and comprising a single strip of thin flexible metal formed 2,935,720 5/60 L i 339-205 X with an L shaped stifiened midsection, and 20 2 933,190 5 50 hbi l 339 217 X stop extensions formed to extend from said stiffened 3,058,091 10/62 Henschen 339 217 X midsection to cooperate with said holder, 3 065 441 11/62 Leonard 39 9 a conductor clamping portion formed on one end of 3:069:65? ,12/62 Grew 339 217 X g g g g fg f t the th nd 3,072,340 1/63 Dean 339-49 an e 0 gae 11cc W1 P 1011 a 0 er 6 25 3,083,345 3/63 Scheller 339 47 of said midsection, said reduced portion being formed as several serpentine folds, bello'ws style, the bend of the first two folds being bent at a small radius which is about equal in size to the thickness of the JOSEPH D. SEERS, Primary Examiner.
ALBERT H. KAMPE, Examiner.