GB2028015A

GB2028015A - Zero insertion force electrical connector

Info

Publication number: GB2028015A
Application number: GB7927365A
Authority: GB
Original assignee: Bunker Ramo Corp
Current assignee: Bunker Ramo Corp
Priority date: 1978-08-07
Filing date: 1979-08-06
Publication date: 1980-02-27
Also published as: IT1122712B; DE2931627A1; JPS5722712Y2; JPS5524737U; IT7924958A0; NL7906001A; FR2433247A1

Abstract

An electrical connector e.g. an edge connector for printed circuit boards comprises an insulating base 5 carrying contacts 1, 2 each with a terminal portion 3, 4 projecting from the bottom and a contacting portion 1a, 2a projecting from the top. An insulated body 8 surrounding portions 1a, 2a has an opening 12 for receiving a male insertion member. The body 8 is movable toward and away from the base and has camming surfaces 14 engaging the tips 1b, 2b of the contacts to cam portions 1a, 2a against respective conductive elements on the insertion member as the body 8 is moved away from the base. An actuation device 15, 16, 17 reciprocates the body 8 relative to the base for camming the contacts into engagement with conductive elements on the male insertion member. <IMAGE>

Description

SPECIFICATION Zero insertion force electrical connector Technical field This invention relates to the field of electrical connectors, and in particular to electrical connectors that receive male insertion members under zero insertion and extraction forces.

Background of the prior art Connectors which have a plurality of contacts and which electrically connect with male insertion members having a corresponding like number of conductive elements thereon are known in the art in a variety of styles and configurations. Among these connectors are those which make electrical contact with the conductive circuit path of a printer circuit board edge. Certain disadvantages result from the use of standard female connectors in which the edge of the printed circuit board is forced into an elongated slot in the connector to spread the plurality of contacts apart sufficient for entry of the circuit board, while ensuring good electrical contact. In particular, especially when a large number of conductive pads on the circuit board edge are to be connected, a great deal of force is required to insert and extract the board from the connector.Thus, there is a tendency to damage the board by flexing it, and additional damage may result at the thin conductive layer immediately adjacent the edge of the board.

Obviously, this renders the connecting and disconnecting operation very difficult. Attempts have been made to avoid this problem by reducing the contact pressure against the board, but this prohibits a secure connection and reduces reliability of the connections.

Briefsummary of the invention The present invention overcomes the above-noted difficulties of the prior art by providing an electrical connector that permits performing connections and disconnections with a male insertion member under zero insertion and extraction forces.

Afurther object of the invention isto provide a connector which makes connection to the male insertion member by pressure contacting the conductive paths thereon after the printed circuit board has been inserted, thus eliminating the difficulties encountered using a conventional connector as mentioned above.

In accordance with the invention, the electrical connector for receiving a male insertion member, i.e.

a printed circuit board or mating male connector part has a connector base of insulative material with a plurality of contacts fixed therein, each contact having a contact terminal portion projecting from the bottom surface thereof and a contacting portion projecting from the top surface thereof. An insulated contact-engaging body encloses the contacting portions of the contacts and additionally provides an opening therein for receiving the male insertion member. The contact-engaging body is movable toward and away from the connector base and has camming surfaces engaging the tips of the contacts to cam the contacting portions of the contacts against respective conductive elements on the insertion member as the contact-engaging body is moved away from the connector base.The connector further includes an actuating device for selectively reciprocating the contact-engaging body relative to the top surface of the base for camming the contacting portion of each contact into engagement with a corresponding conductive element on the male insertion member.

The connector is operative to provide zero insertion and extraction forces for connectors which contain a single aligned row of contacts or a pair of parallel facing rows of contacts, depending upon whether a single-sided printed circuit board or a double-sided board is to be accommodated, respectively.

In a preferred embodiment, the base member has a deep groove formed therein and extending longitudinally of the connector for receiving a depending guide portion of the contact-engaging body to allow for reciprocation of the depending guide portion and confined within the groove even at both extremes of the positioning of the reciprocating contactengaging body.

The contact-engaging body forms the upper part of the connector and includes a series of contact cavities along the inner walls thereof, each cavity having, at its upper end, a sloping camming shoulder for engaging the tip of the contact in that cavity and moving the contact inwardly against the printed circuit board.

A preferred form of the actuating device for reciprocating the contact-engaging body is in the form of an open rectangular frame member encompassing the contact-engaging body and cooperating with an engagement shoulder on the exterior surface of the contact-engaging body formed by undercutting a portion of the latter. A plurality of operating links have their opposite ends pivotally pinned to the connector base and frame member, and one of the operating links has an extension protruding beyond the top or bottom surface of the connector and serving as an operating handle. When the operating handle is pivoted, the link portion thereof, as well as all of the other operating links, move the frame member up and down relatively to the connector base due to the confinement of the frame member about the periphery of the contact engaging body.

In operation, movement of the operating handle to cause the frame member to rise serves to lift the contact-engaging body against the spring action of the contacts to permit the camming surfaces to move to the contacts inwardly against the printed circuit board. When the operating handle is moved in the other direction, the frame member moves away from the engagement shoulder of the contactengaging body permitting the spring action of the contacts to act in reverse, i.e. the tips of the contacts press against the camming surfaces and force the contact-engaging body to return to its initial position, and this simultaneously allows the contacts to flex outwardly and release pressure from against the male insertion member.

Brief description of the drawings The invention will now be described in detail with reference to the accompanying drawings represent ing preferred embodiments of zero insertion force connectors according to the present invention. In the drawings: Figure 1 is a perspective view of the connector made in accordance with the invention with the left side thereof removed to show a cross section of the inner workings of the connector; Figure 2 is an exploded view of the contactengaging body removed from the connector base; Figure 3 is an inverted perspective view of the contact-engaging body; Figure 4 is a perspective view of the operating frame member which cooperates with the contactengaging member of Figure 2 in operating the connector in accordance with the invention.

Figure 5 is an elevational view of the complete connector with the handle in a vertical position to effect electrical contact with a male insertion member (not shown); Figure 6 is a cross-sectional view taken along the lines 6-6 in Figure 5; Figure 7 is an elevational view somewhere to that of Figure 5 but showing the handle in its lowered position which permits release of the male insertion member (not shown); Figure 8 is a cross-sectional view of the connector taken along the lines 8-8 of Figure 7; Figure 9 is a perspective view of an alternate embodiment of the connector showing an extended length for the operating handle; and Figure 10 is a cross-sectional view similar to that of Figure 6 that showing only a single row of contacts.

Detailed description of the invention Referring to Figure 1, it can be appreciated that the connector of the prevent invention is comprised of a connector base 5, a plurality of electrical contacts 1 fixed in the connector base 5, a contact-engaging body 8, an operating frame member 15 for moving the contact-engaging body 8 toward and away from the connector base 5, and a plurality of operating links 17 pivotally connected to the connector base 5 and frame member 15 for simultaneously acting in concertto lift and lower frame member 15 as the operating handle 16 is pivoted. The lifting of frame member 15 and contact-engaging body 8 causes the free upper ends 1b of the contacts 1 to be forced inwardly of the connector and against a male insertion member inserted in the connector.

It will be obvious that the male insertion member can be a printed circuit board, a ribbon cable, a mating male connector, or the like. However, for the purposes of the following discussion, only a printed circuit board will be referred to for simplicity of explanation.

The contacts 1 and 2 include terminal portions 3 and 4, respectively extending below the bottom of the connector base 5 for making connection to a cable, wire, or other electrical device. Above the connector base 5, the contacts 1 and 2 bend inwardly to form curved bight portions 1 a and 2a, and then bend back outwardly then upwardly to form the contact tips 1 band 2b.

The contact-engaging body 8 is formed with a plurality of contact cavities 13 aligned along the inner faces thereof with the connecting bight portions 1a and 2a of the contacts 1 and 2 lying adjacent the inner edge of the cavity with sufficient space between the bight portions 1a and 2a to allow a printed circuit board to be inserted through elongated through-hole 12 with zero insertion and extraction forces. That is, in the position of the contacts in Figure 1, there are no lateral forces applied to the printed circuit board (not shown) by contacts 1 and 2.

The contact-engaging body 8 is reciprocable relative to the connector base and yet maintains alignment with the connector base by the provision of a groove 5a receiving an undercut skirted portion 11 of the body 8 in loose relationship. As body 8 is reciprocated vertically as shown in Figure 1, the contact camming shoulders 14 move the tips 1b and 2b of the contacts inwardly to effectuate connection of the respective bight portions la and 2a against the printed circuit board.

An engagement shoulder 10 for engagement with frame member 15 is formed by virtue of the undercut portion 11, and the provision of camming shoulder 14 internally of the body 8 defines an enlarged upper body portion 9 of the body 8, giving the body 8 a T-shape as can best be seen in Figure 2.

The formation of grooves 5a in connector base 5 define raised rectangular strips 7 along the longitudinal edges of connector base 5 upon which operating links 17 are pivoted by means of pins 20. The upper ends of links 17 are pivoted on frame member 15 by pins 21. The operating handle 16 is merely an extension of an operating link 17 on the rear side of the connector as shown in Figure 1, and it can be appreciated that, utilizing known mechanical analysis, moving operating handle 16 to the left in Figure 1 will serve to raise frame member 15, and in turn body 8, while moving operating handle 16 to the right in Figure 1 will lowerframe member 15 moving it away from engagement shoulders 10.When frame member and body 8 are raised, each contact is cammed inwardly against the printed circuit board (not shown), and when frame member 15 is lowered, the spring returned action of the contacts push against shoulders 14 to return body 8 to its initial pOsition.

The center rectangular strip 6 may serve to space the contacts of a double-row connector and add strength to the connector base 5. They also provide a stop for an inserted board thereby defining the penetrating limit for the board.

Figure 2 illustrates the basic departure from prior art connectors in which the upper and lower portions of the connector body are of separate construction compared to a unitary connector body construction of the prior art. In Figure 2, the connector body is shown in two pieces, contact-engaging body 8 and connector base 5. The grooves 5a are best seen in Figure 2, and the manner in which the small ends of the body 8 are allowed to reciprocate relative to connector base 5 is also visible.

Figure 3 shows an inverted position of body 8 to indicate the rectangular form of the skirt portion 11.

In Figure 4, the simplicity of the form of operating frame member 15 can be seen. It will also be appreciated that operating member 15 is slightly longer than body 8 and base 5 to allow for a certain amount of longitudinal movement of the frame member as operating handle 16 is rotated. In other words, rotating operating handle 16 not only serves to lift and lower frame member 15, but also moves it back and forth longitudinally along the exterior surface of the undercut skirt portion 11.

Figure 5 illustrates the position of the links 17 and handle 16 when body 8 is forced upwardly to cam the contacts 1 and 2 against the printed circuit board.

Figure 6 shows a printed circuit board 18 having conductor pads 19 being contacted under pressure by contacts 1 and 2. In this figure, it can be seen that body 8, although having been lifted by frame member 15, has its skirt portion 11 still contained within groove 5a.

In the relaxed position of handle 16 as shown in Figure 7, frame member 15 is disengaged from engagement shoulder 10, and in this position the contacts are allowed to spring outwardly of the connector and away from the printed circuit board 18, as best seen in the cross-sectional view of Figure 8.

When the density of connectors mounted in an apparatus is such that reaching next to the connector body to operate handle 16 becomes impossible or difficult, handle 16 may extend even further than that shown in the previous figures and may include an extended portion 16a as seen in Figure 9. The tip of handle 16 can therefore be accessible even beyond the outermost extremes of the inserted printed circuit board.

In Figure 10, the connector base 5 is shown to affix only a single row of contacts 1. In this figure, frame member 15 operates in a manner similar to that previously described, but only one set of camming shoulders 14 is needed and shown in the figure.

Figure 10 also shows, in the dotted lines, the possibility of extending handle 16 below the connector, that is in the direction of the terminating portion of contacts 1, so that engagement and release of the contacts against the printed circuit board can be accomplished from the terminal side of the connector when it is necessary or advisable to do so.

Needless to say, the spacing between contacts 1 in the body 8 correspond to spacing of conductive pads on the printed circuit board, and the optimum pressure for reliable connection to the board is determined when the handle 16 is in its operating position in which body 8 is raised to its upper limit, preferably when the handle is straight up. The tension is determined by many factors, among which are the curvature of the bight portions la and 2a, and the position of contact on the board is determined, in part, by the height of center strip 6 of base 5.

From the foregoing, it can be readily realised that this invention can assume various embodiments.

Thus, it is to be understood that the invention is not limited to the specific embodiments described herein, but is to be limited only by the appended

Claims

claims. CLAIMS

1. An electrical connector for receiving a male insertion member under zero insertion force and after being fully inserted in the connector, said connector comprising: a connector base of insulative material having top and bottom surfaces; a plurality of contacts fixed in said connector base, each having a contact terminal portion projecting from said bottom surface and a contacting portion projecting from said top surface; a movable insulated contact-engaging body enclosing the contacting portions of said contacts, said body having an opening therein for receiving the male insertion member and having a camming surface engaging a cooperating part of each contact to cam said contacting portion against a conductive element on the insertion member as said contact-engaging body is moved away from said base; and means for selectively reciprocating said contact-engaging body relative to said top surface of said base for camming said contacting portion into engagement with said insertion member conductive element.

2. The connector as claimed in Claim 1,wherein: said connector base and contact-engaging body are elongated and have approximately the same lengths; and said connector includes a plurality of said contacts aligned in a row longitudinally of said base and contact-engaging body.

3. The connector as claimed in Claim 2, wherein said connector includes two parallel facing rows of said contacts.

4. The connector as claimed in Claim 2, wherein: said connector base has a groove formed therein, and said contact-engaging body has a depending guide means for loosely fitting in said groove and reciprocating within said groove as said contactengaging body reciprocates relative to said top surface.

5. The connector as claimed in Claim 4, wherein: said groove extends in a rectangular pattern about said base top surface; and said contact-engaging body is rectangularly shaped with said depending guide means comprising a rectangular skirt portion reciprocable in said rectangular groove.

6. The connector as claimed in Claim 2, wherein: said contact-engaging body includes a plurality of contact cavities along at least one longitudinal inner wall thereof; said camming surface including, for each said cavity, a sloping camming shoulder; and said contacting portion of each said contact has a bight portion bowed inwardly of said connector, and a tip portion at the upper free end thereof engagable by said camming shoulder, said tip portion defining said contact cooperating part; whereby, upon upward movement of said contact-engaging body, said tip portion is moved inwardly by the camming action of said camming shoulder, and said bight portion is moved inwardly to engage the respective conductive element of said male insertion member.

7. The connector as claimed in Claim 2, wherein: said contact-engaging body has a stepped undercut portion along the sides thereof defining an engagement shoulder adjacent, but spaced from, its upper face; and said means for reciprocating includes a frame member movable toward and away from said base top surface, said frame member having means for engaging said engagement shoulder to move said contact-engaging body upwardly relative to said base top surface.

8. The connector as claimed in Claim 7, wherein said means for reciprocating includes at least one operating link pivotably joined at its ends to said base and said frame member, respectively.

9. The connector as claimed in Claim 8, wherein one of said links has an extended portion defining an operating handle protruding beyond the top or bottom surface of said connector, whereby movement of said handle in one direction forces said frame member upwardly against said engagement shoulder, and movement of said handle in the opposite direction moves said frame member away from said engagement shoulder.

10. The connector as claimed in Claim 8, wherein: said frame member is rectangular and open in its center to completely encompass said contactengaging body, the width of the opening in said frame member being slightly greater than the width of said contact-engaging member undercut portion and less than the width of said contact-engaging member above said engagement shoulder.

11. The connector as claimed in Claim 9, wherein, when said handle moves said frame member away from said engagement shoulder, said contacts press against said camming surface to move said contact-engaging body downwardly and thereby allow said contacting portion to move away from engagement with the conductive element of the male insertion member.

12. The connector as claimed in Claim 10, wherein the opening in said frame member has a length greater than the length of said connector base and contact-engaging body to accommodate for longitudinal movement of said frame relative to said base and said body as said operating links pivot to raise and lower said frame member.