Geometrical instruments
Patent
1985-11-25
1987-03-03
McGlynn, Joseph H.
Geometrical instruments
339258P, H01R 1311
Patent
active
046471405
DESCRIPTION:
BRIEF SUMMARY
This invention is concerned with electrical connectors.
In the telecommunications field, especially in the private sector where telephone circuits are provided for continuous use, there is a requirement for accessing and testing these circuits without interrupting them so that they can remain in service and in use while testing takes place. These private telephone circuits, or lines, are not part of the public dial-up network and therefore require specialised testing equipment as is provided, for example, by the Hewlett-Packard HP37100 series remote access testing system.
It is a primary requirement that the test equipment must be installed in a circuit so that it can be disconnected from or connected into that circuit without breaking transmission in that circuit. To achieve this, the test equipment typically comprises a number of "access cards" which can be connected into the circuit to be tested, each access card having mounted thereon a plurality of relays, the relays operating in a manner such as to maintain continuity of circuit, and to switch the circuit to the test equpment as hereinafter described. Each access card is essentially a printed circuit board having conductive traces thereon leading to and from relays mounted on the board and extending to an edge of the board on both surfaces thereof. The traces thus provide edge connectors along the edge of the board, which edge connectors are arranged to be held in electrically-conductive spring clips which provide normally contacting jaws when the board is not urged therebetween and can be forced apart by the edge of the board when the test equipment is connected in circuit.
BRIEF DESCRIPTION OF THE DRAWINGS:
FIG. 1 is a schematic circuit diagram of an access card in a single circuit line.
FIG. 2 depicts an element of a prior art spring clip.
FIGS. 3a, 3b, and 3c depict an edge portion of a circuit board in progressive stages of insertion into a prior art spring clip.
FIGS. 4a and 4b depict the extremities of leaf-spring portions of a prior art spring clip in exaggerated form as the clip is sprung.
FIGS. 5a and 5b depict examples of corrosion build-up between a circuit board and leaf-spring portions of a prior art spring clip while the circuit board is inserted, and corrosion build-up between leaf-spring portion of a prior art spring clip after the circuit board is removed.
FIG. 6 shows a perspective view of a connector according to the invention.
FIG. 7 shows a side view of a connector according to the invention in a relaxed condition.
FIGS. 8 and 9 show exaggerated views illustrating a characteristic feature of the present invention.
FIG. 1 is a schematic circuit diagram which illustrates the principle of interconnection of an access card in a single circuit line, of which in practice there are many. The line 100 includes a spring clip indicated by the box 102, the clip comprising jaws indicated by the two arrowheads 104, 106. As illustrated in FIG. 1, the jaws 104, 106 are sprung apart and make contact with edge connectors 110, 112 on opposite surfaces of a circuit board, the connectors being electrically connected to relays RL1, RL2 mounted on the board.
Provided that the jaws 104, 106 make good electrical contact with the connectors 110, 112 continuity is maintained in the line 100 via the closed contact 115 of the relay RL1, while the contacts of the relay RL2 remain open. When it is desired to test the circuit, the contacts of the relay RL2 are closed and those of the relay RL1 are opened to divert the circuit through an access bus 116 to test equipment provided at a remote location. In normal operation, the circuit is maintained through the contact 115 of the relay RL1 and only for occasional intervals is the circuit switched through the relay RL2 to the remote test equipment. Occasionally, a component, e.g. a relay, of an access card can fail and at that point in time it is necessary to withdraw the access card from use. At this point the access card is physically moved so that the edge connectors thereof are withdrawn from between the ja
REFERENCES:
patent: 4087151 (1978-05-01), Robert et al.
patent: 4285565 (1981-08-01), Kirby
Bring Karl E.
Hewlett -Packard Company
McGlynn Joseph H.
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