EP0002114B1

EP0002114B1 - Zero insertion force printed circuit board edge connector

Info

Publication number: EP0002114B1
Application number: EP78300558A
Authority: EP
Inventors: Marvin Leo Yeager; Jerome Andrew Desso
Original assignee: AMP Inc
Current assignee: TE Connectivity Corp
Priority date: 1977-11-14
Filing date: 1978-10-27
Publication date: 1981-01-07
Also published as: ES475022A1; IT1100681B; IT7829484A0; BR7807359A; JPS5482078A; CA1088170A; DE2860439D1; EP0002114A1; JPS616511B2; MX144500A

Description

There is described in DE A 2,207,122, a zero insertion force printed circuit board edge connector, comprising an insulating housing having a channel therein for receiving a printed circuit board along a board insertion path, a row of electrical contacts positioned on each side of the channel and extending in a longitudinal direction thereof, each contact having a contact surface for engaging the printed circuit board when such has been inserted into the channel, and contact-operating means comprising a cam mean movable to displace a contact driving means in the direction in which the board insertion path extends, to move each contact between a board receiving first position in which the contact surface of the contact is withdrawn from the board insertion path and a board engaging second position in which such contact surface intersects the board insertion path, the contact-operating means being formed with relatively stepped surfaces succeeding one another in the longitudinal direction of the channel so that the contacts are moved sequentially between their first and second positions, in response to the movement of the cam means.
In this known connector, the stepped surfaces are provided on the cam means and the contact driving means are in the form of a plurality of contact driving members each of which is engageable with only two opposed contacts of the rows.
The present invention is intended to provide a connector of the above kind which is substantially simplified in that it has only one contact driving member despite the fact that the connector may comprise a multiplicity of contacts in each row.
A connector as defined in the first paragraph of this specification is, according to the present invention therefore, characterised in that the relatively stepped surfaces are provided on the contact driving means, these relatively stepped surfaces serving sequentially to engage the contacts of the rows; and in that the contact driving means is in the form of a single contact driving member which comprises a base from opposite edges of which extend side walls, the stepped surfaces being formed in the free longitudinal edges of the side walls, so that the height of each side wall increases in one longitudinal direction of the channel.
Although according to FR A 2,278,222 beads of different heights may be provided on a contact driving means sequentially to move the contacts of an electrical connector between contact making and contact breaking positions, at least one contact driving member is, and indeed must be, provided for each row of contacts.
In a connector according to the invention, each stepped surface may be conveniently dimensioned to engage a group of contacts connected to a respective circuit, for example a power circuit, a ground circuit or a signal circuit, whereby these circuits are made and broken sequentially.
Although there is disclosed in United States Patent Specification No, 3,648,221 a zero insertion force connector which can be programmed by varying the number of contact engaging projections on a cam member of the connector, there is no suggestion in this prior patent specification that the cam member can be arranged sequentially to displace the contacts.
According to United States Patent Speci- ftcatio_'n No. 3,475,717 two rows of contacts of a zero insertion force printed circuit edge connector may be independently driven between board engaging and board disengaging positions. However, all the contacts of each row can be driven only simultaneously between positions.
The state of the art at this time is further exemplified by United States Patent Specifications Numbers 2,770,788; 3,037,181; 3,366,916; 3,451,490; 3,576,515; 3,744,805; 3,793,609; 3,897,991; 3,889,234; 3,982,807; 4,047,782; 4,076,362 and 4,077,688.
For a better understanding of the invention reference will now be made by way of example to the accompanying drawings, in which:-

Figure 1 is a perspective view of a sequentially actuable zero insertion force printed circuit board edge connector which embodies the invention, the connector being shown in a board engaging condition;
Figure 2 is a longitudinal vertical section through the connector of Figure 1;
Figure 3 is a top plan view of the connector shown partly in horizontal section, the connector being shown in an intermediate condition;
Figure 4 is a transverse vertical section through the connector with contacts thereof in a closed position;
Figure 5 is a partial transverse vertical section, through the connector with the contacts in an open, board receiving position; and
Figure 6 is a foreshortened perspective view of a contact driving member of the connector.

The connector comprises four primary components, namely, an elongate insulating housing. 12, a cam member 14, a contact driving member 16, and a plurality of spring electrical contacts 18.
The housing 12 has mounting flanges 20 and 22 at the opposite ends thereof for securing the connector to a mother printed circuit board 24 by means of fasteners 26 (Figure 2). The housing 12 has formed therein an elongate central guide channel 28 for receiving a daughter circuit board 30, the longitudinal side walls 2 of the housing 12 being formed with spaced ribs 22 projecting inwardly from the side walls 2 and defining recesses 34. Each recess 34, which communicates with the channel 28, receives a respective contact 18. A passage 36 extends from the lower (as seen in Figure 4) end of each recess 34 through a base 38 of the housing 12. The base of the channel 28 is formed with a central longitudinal groove 40 which communicates with a slot 41 in one end of the housing 12 and with an opening 39 in the other end thereof, opposed recesses 42 being formed in the upper (as seen in Figure 1) portions of the side walls of the slot 41 and opening into the upper surface of the housing 12.
The contact driving member 16, which lies in the channel 28 is, as best seen in Figure 6, channel shaped, having a base 44 and parallel side walls 46 and 48, the free longitudinal edges of the side walls 46 and 48 being formed, as best seen in Figure 6, with steps 49 so that the height of the free longitudinal edges of these side walls increases from right to left, as seen in Figures 2 and 6. These free longitudinal edges, which have chamfered outer faces 47, comprise at least two relatively stepped surfaces succeeding one another in the longitudinal direction of the channel 28. The ends of the base 44 have bevelled surfaces 50 and 52. As shown in Figures 2, 4 and 5, the outer or lower surface of the base 44 faces the mouth of the groove 40.
The cam member 14 comprises an elongate cam portion 60 and a resilient, loop-shaped, handle 62. The cam portion 60, which is slidably and rotatably received in the groove 40, is shaped, as seen in cross-section (Figures 4 and 5), as an elongate quadrilateral having parattet sides joined by radii. The handle 62, which has a free end portion 64, extends from the cam portion 60 externally of the housing 12, for rotating the cam portion 60 about its longitudinal axis and for sliding the cam portion 60 longitudinally of the groove 40.
The contacts 18 may be formed for example by stamping and forming metal strips, or by rolling and forming wire. Each contact 18 has a resilient, inwardly bowed, board engaging contact surface 54 and a terminal portion 56 which extends through one of the passages 36 for mechanical and electrical connection to a printed conductor 58 (Figure 2) on the mother board 24 and to further conductors (not shown) and thus to electrical circuits (not shown) by wire wrap connections (not shown), for example. Each contact 18 is retained against withdrawal from the housing by means, for example, of a locking lance (not shown) or by the flow of the housing material during manufacture of the connector, into an aperture (not shown) in the contact 18.
The free end portion 64 of the handle 62 is receivable in the recesses 42 of the housing, for the avoidance of unintended rotation of, and removal, in the direction of the arrow B in Figure 1, from the connector of, the cam member 14.
The connector is assembled by inserting the cam portion 60 of the member 14 into the groove 40 and the contact driving member 16 into the channel 28, aided by the bevelled surfaces 50 or 52.
When the cam portion 60 is positioned as shown in Figures 1, 2 and 4 so that its broader sides 61 lie parallel to the base of the groove 40 and to the base 44 of the driving member 16, the driving member 16 takes up a retracted position so that all the surfaces 54 of the contacts 18 are in a board engaging position, in which they project into the insertion path of the board 30 into the channel 28, as best seen in Figure 4.
As the handle 62 is rotated in the direction of the arrow A in Figure 3, the cam portion 60 is rotated about its longitudinal axis towards the position of Figure 5 in which the broader sides 61 of the portion 60 extend normally of the base of the groove 40 and of the outer surface of the base 44.
During such rotation of the handle 62, the driving member 16 is progressively forced by the cam portion 60 in a direction normal to the base of the groove 40 and thus of the base of the channel 28, and away therefrom, so that the chamfered faces 47 of the free longitudinal edges of the side walls 46 and 48 of the driving member 16 sequentially engage respective groups of the contacts 18 to move the contact surfaces 54 thereof outwardly into the recesses 34 and thus into their board receiving positions shown in Figure 5, in which the contact surfaces 54 are withdrawn from the insertion path of the board 30. As shown in Figure 3, the leftward group of contact surfaces, 54a, are first driven into their board receiving positions followed by the next adjacent group of contact surfaces, 54b, and so on in predetermined sequence.
When all the groups of contact surfaces 54 have thus been moved into their board receiving positions, the daughter board 30 is inserted into the channel 28 and the handle 62 is rotated back to its position of Figure 1, to move the groups of surfaces 54 sequentially back into their board engaging positions. The handle 62 is then pushed rightwardly, i.e. in the opposite direction to that of the arrow B, towards its position of Figure 2 and the free end portion 64 of the handle 62 is resiliently introduced in the recesses 42 so that the contact surfaces 54 are secured in their engagement with the daughter board 30. The daughter board 30 can be subsequently released from the connector by again rotating the handle 62 in the direction indicated by the arrow A, after removing the free end portion 64 of the handle 62 from the recesses 42 and withdrawing the handle 62 in the direction of the arrow B in Figure 1. The groups of contacts 18 are thereby released sequentially so that damage to the circuits to which the contacts 18 are connected and which might arise if the contacts 18 were simultaneously disconnected from the conductors of the board 30, can be avoided.
There are many cases in which it is either desirable or necessary, or both. for power, ground and signal circuits to be broken sequentially, for mechanical or electrical reasons. For example, where bi-polar logic devices, which have both positive and negative power supplies are employed. the latter being referenced to ground, it may occur if the ground circuit is first broken, that supply voltages will "add" across an individual gate element and so destroy it. In digital electronic systems, for example, the generation, by removal of the daughter board, of spurious transients leading to data falsification can be avoided by arranging for the power circuit to be first broken.
The term printed circuit board is used herein in its most general aspect and is intended to include any circuit boards, cards or substrates on which electrical conductors have been provided by printing or by analogous means.

Claims

1. A zero insertion force printed circuit board edge connector, comprising an insulating housing (12) having a channel (28) therein for receiving a printed circuit board (30) along a board insertion path, a row of electrical contacts (18) positioned on each side of the channel (28) and extending in a longitudinal direction thereof, each contact having a contact surface (54) for engaging the printed circuit board (30) when such has been inserted into the channel (28), and contact-operating means comprising a cam means (60) movable to displace a contact driving means (16) in the direction in which the board insertion path extends, to move each contact (18) between a board receiving first position in which the contact surface (54) of the contact (18) is withdrawn from the board insertion path and a board engaging second position in which such contact surface (54) intersects the board insertion path, the contact-operating means being formed with relatively stepped surfaces (47) succeeding one another in the longitudinal direction of the channel (28) so that the contacts (18) are moved sequentially between their first and second positions, in response to the movement of the cam means (60), characterised in that the relatively stepped surfaces (47) are provided on the contact driving means (16), these relatively stepped surfaces serving sequentially to engage the contacts (18) of the rows; and in that the contact driving means is in the form of a single contact driving member (60) which comprises a base (44) from opposite edges of which extend side walls (46 and 48), the stepped surfaces (47) being formed in the free longitudinal edges of the side walls (46 and 48), so that the height of each side wall increases in one longitudinal direction of the channel (28).

2. A connector according to Claim 1, characterised in that each stepped surface (47) on the contact driving member (16) is dimensioned to engage a group of the contacts (18) simultaneously.

3. A connector according to Claim 1 or 2, characterised in that the contact driving member (16) is positioned between the mouth of the channel (28) and cam member (60) so as to rest upon the cam member (60) which is rotatable in a groove (40) in the base of the channel (28) about an axis extending longitudinally of the channel (28) and is also slidable lengthwise of the groove (40), the cam member (60) having a handle (62) which extends exteriorly of the housing (12) and is insertable in a recess (42) therein, to secure the cam member (60) to the housing (12) and to restrain rotation of the cam member (60) relative to the housing (12), when the contacts (18) are in their second position.

4. A connector according to Claim 1 or 2, characterised in that the cam member (60) has a handle (62) which extends exteriorly of the housing (12) and by means of which the cam member (60) can be rotated relative to the housing (12), the handle (62) having a free end portion (64) which can be moved relative to the housing (12) to allow the free end portion (64) of the handle (62) to be lodged in a recess (42) in the housing (12).