GB2167260A

GB2167260A - Improvements in or relating to signal connectors

Info

Publication number: GB2167260A
Application number: GB08527301A
Authority: GB
Inventors: Brian Cordwell
Original assignee: Plessey Co Ltd
Current assignee: Plessey Co Ltd
Priority date: 1984-11-20
Filing date: 1985-11-06
Publication date: 1986-05-21
Also published as: GB8527301D0; GB8429242D0

Abstract

A signal connector to facilitate connection of optical drivers and receivers to fibre optic transmission paths in rack mounted equipment. The active component (LED/Laser or photodiode) 10 is mounted in the connector housing 11 associated with a printed circuit board 1. The fibre optic is terminated in the housing of the corresponding connector 16 so that fitting of the printed circuit board to the rack effects both electrical and optical interconnections. A connector may also have an active element 17 in place of the fibre termination. <IMAGE>

Description

SPECIFICATION Improvements in or relating to signal connectors The present invention relates to signal connectors and in particular to connectors in which at least one connectable transmission path carries an optical signal.

The use of fibre optics as transmission paths in communications is well established technique. However, the major problem with such transmission paths is the difficulty of making connections to the fibres particulary if a demountable connection is required.

In recent times there have been many advances in fibre optic connectors but connections in optical fibres invariably introduce additional transmission losses and require considerable skill to effect.

In a communications environment much circuitry is involved and to assist maintenance such circuitry is normally based on printed circuit boards which have an associated male connector either wired to one edge or integral with the board. The printed circuit boards making up the total communication environment slide into shelves of racks, each position to which a card fits having an associated female connector. It is here noted that the female connector may be wired to the edge of the circuit board with the associated male connector provided in the shelf position. Mating of the respective male and female connectors then effects interconnection of up to, say, forty electrical signal transmission paths. However, in known systems optical signal transmission paths to or form optical receivers or transmitters on a circuit board require a separate connection operation.

For the avoidance of doubt the term ''active optical component" as used therein means either a transmitting device which converts an electrical signal at its input to an optical signal at its output or a receiving device which converts an optical signal at its input to an electrical signal at its output. The term may also apply to an optical transmitter/receiver arrangement.

It is an object of the present invention to provide connector arrangements in which demountable connections between optical transmission paths and active optical components may be effected in a simple and convenient manner.

According to the present invention there is provided a connector arrangement of the kind comprising interconnectable male and female connector housings each having means to provide a demountable interconnection of at least one signal transmission path wherein one of said connector housings carries at least one active optical component of which the optical input or output is aligned with respect to that housing and the other of said connector houszings carries at least one optical fibre termina tion which is correspondingly aligned with re spect to that housing such that effecting con nection between the housings effects a direct connection of an optical transmission path so terminated to said active optical component.

Preferably said male and female connector housings also carry at least one respective electrically conductive contact member ar ranged to interconnect an electric signal transmission path.

Said connector arrangement may be of the kind providing for interconnection between a printed circuit board which carries a male or female connector and a shelf arrangement in which said printed circuit board may be mounted, the shelf arrangement preferably car rying the corresponding female or male con nector.

Each of the connector housings may carry a plurality of electrically conductive contacts which if the male connector is carried by the printed circuit board may be integral with tracks of the printed circuit board.

In an alternative use of the connector ar rangement there is provided a connector ar rangement of the kind comprising interconnec table male and female connector housings each having means to provide a demountable interconnection of at least one signal transmis sion path wherein each of said connector housings carries at least one respective active optical component corresponding ones of which are respectively a transmitter and a re ceiver, the respective optical output and input of which are aligned with respect to the hous ing such that effecting connection between the housings effects alignment of the respec tive output and input to provide an electrically isolated interconnection of a transmission path in the manner of an opto-isolator.

Connector arrangements in accordance with the invention will now be described by way of example only with reference to the accom panying drawing of which: Figures 1 and 2 show schematically prior art connection arrangements; and Figure 3 shows schematicaliy a connector arrangement in accordance with the invention.

Referring to the drawing in each of the figures part of a printed circuit board 1 is shown. The printed circuit board is inserted in slides or card guides (not shown) in a shelf of a rack (not shown) which will hold a number of printed circuit boards (such as 1) in a hori zontal row. The rear of the rack depicted by a part of its back plane 2 normally carries a number of female connectors (but as previ ously noted may carry a number of male con nectors) which effect electrical connection be tween an edge connector of each printed cir cuit board 1 and to other printed circuit boards of the system for example.

In Figs. 1 and 2 the problem of connecting and disconnecting an active optical component 3 may be seen. Consider first the component 3 of Fig. 1 which may be a transmitter or receiver module of the kind available from Belling Lee Limited of the United Kingdom.

The component 3 comprises an internal light emitting device (or light receiving device in the case of a receiver) which is accurately aligned in manufacture with an integral connector 4.

Electronic drive circuitry is provided in the module 3 the pins of which may be soldered to the printed circuit board in the usual manner.

An optical fibre 5 having a corresponding termination (in this case a female termination) 7 passes through an aperture 6 provided in the back plane 2 and must be attached directly to the connector 4.

It will be appreciated that, if a number of printed circuit boards 1 are mounted side by side in a rack, connection of the optical fibre 5 to the active optical component 3 cannot be carried out with the board 1 in its "home" position. Thus, to permit connection or disconnection of the active optical component 3 some excess length of the fibre 5 must be provided. Thus when inserting a board to the rack excess fibre length ("slack") must be brought to the front of the rack, the connection of the terminations 7 and 4 must be effected and then insertion of the card to effect electrical connections may take place.Care in inserting the card to its home position is necessary to avoid damaging the slack section of the optical fibre 5 and to avoid introducing any tight bends in the fibre 5 which would introduce an excessive loss in transmission power and which may cause physical damage to the fibre.

In the system of Fig. 2 to which reference is now made the active optical component 3 is of the kind available from Plessey Optoelectronics and Microwave Ltd in their HRCL series of transmitter and receiver devices.

In this case the active optical component 3 includes integral driver or receiver circuitry and a light emitting or receiving device and an integral fibre length 8 accurately aligned with the emitting or receiving device during manufacture.

In this case the optical fibre 5 is connected to a connector 9 which may be provided towards the rear of the printed circuit board 1 and which terminates the integral fibre length 8 of the active optical component 3. Thus, although it is possible with this kind of device to adjust the fibre length 8 when assembling components to the printed circuit board 1 so that on insertion or removal of the board 1 to its shelf position no damage (by snagging on adjacent boards for example) occurs, such insertion or removal still necessitates two independant operations for connecting optical and electrical transmission paths.

Referring now to Fig. 3, in the system of the present invention the optically active part of an active optical component is separated from the driving or receiving circuitry thereof.

Thus a light emitting diode 10 or laser for example with an associated lens system if necessary in a transmitting device is accurately fitted to a plastics housing 11 of a male or female edge connector which also carries electrical contacts in known manner. The electrical signal input of the transmitting device is provided with soldered contacts 12 which may be of the same form as the solderable portion of the electrical contacts of the connectors.

Driver circuitry 14 for the transmitter is provided, typically in a dual-in-line circuit package and normal printed circuit tracks 15 of the printed circuit board 1 are used to interconnect the driver circuitry 14 and the optical component 10.

It will be realised that a receiver, the photosensitive component is accurately aligned in the plastics housing 11 of the connector in the same manner as the light emitting diode 10 with its associated amplification circuitry being mounted on the printed circuit board 1.

It will be appreciated that the electrical contacts of the male edge connector when associated with the circuit card may be at least partially integral with the printed circuit tracks of the printed circuit card in which case the plastics housing 11 containing the optical device 10 may be attached to the card in alignment with the electrical contacts so provided.

In the opposite connector part of the connector arrangement, a plastics housing 16, of the connector carrying corresponding electrical contacts in known manner is mounted on the back plane 2. The plastics housing 16 carries a fibre termination 17 accurately fitted thereto and arranged to terminate the fibre 5 at a position which, when the printed circuit board 1 is fitted to the shelf, will align the optical transmission path with the light emitting or receiving device 10.

Once again the termination 17 may include a lens system if necessary.

Thus, using the arrangement of the present invention removal or insertion of a printed circuit card carrying an active optical component is a single operation, the connector arrangement being such that both optical and electrical transmission path interconnections are effected simultaneously.

Other benefits of the invention will be notedincluding avoidance of easily damaged optical fibre links needing to run along side cards and the simplicity of incorporating optical devices into normal printed circuit board assembly practices.

It will be appreciated that both the male connector housing and the female connector housing may be provided with respective active optical components one being a receiver (photodiode) and the other a transmitter (e.g.

a laser or light emitting diode) so as to pro vide an electrically isolated interconnection between rack wiring (which may be at a comparatively high voltage) and the electrical circuit of the printed circuit card 1.

It will be realised that whilst as herein described the printed circuit cards are inserted in a rack in horizontal rows, the invention is equally applicable to rack equipment in which the cards are inserted invertical "stacks".

Claims

1. A connector arrangement of the kind comprising interconnectable male and female connector housings each having means to provide a demountable interconnection of at least one signal transmission path wherein one of said connector housings carries at least one active optical component of which the optical input or output is aligned with respect to that housing and the other of said connector housings carries at least one optical fibre termination which is correspondingly aligned with respect to that housing such that effecting connection between the housings effects connection of an optical transmission path so terminated to said active optical component.

2. A connector arrangement of the kind comprising interconnectable male and female connector housings each having means to provide a demountable interconnection of at least one signal transmission path wherein each of said connector housings carries at least one respective active optical component corresponding ones of which are respectively a transmitter and a receiver, the respective optical output and input of which are aligned with respect to the housing such that effecting connection between the housings effects alignment of the respective output and input to provide an electrically isolated interconnection of a transmission path in the manner of an opto-isolator.

3. A connector arrangement as claimed in claim 1 or 2 wherein said male and/or female connector housings also carry at least one respective electrically conductive contact member arranged to interconnect an electric signal transmission path.

4. A connector arrangement as claimed in claim 3 wherein the interconnection between a printed circuit board carries a male or female connector and a shelf arrangement in which said printed circuit board is to be mounted, the shelf arrangement carrying the corresponding female or male connector.

5. A connector arrangement as claimed in any preceeding claim wherein each connector housing carries a plurality of electrically conductive contacts.

6. A connector arrangement as claimed in claim 5 wherein with the printed circuit board carrying a male connector it is integral with the tracks of the printed circuit board.

7. a connector arrangement substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.