CA1245490A - Fiber optic connector - Google Patents

Abstract

ABSTRACT.

There is described a fiber optic connector. Within the fiber optics it is a problem that contacts may be contaminated, for example by dust and dirt so that the light transmission becomes poor. Each of the two con-nector parts (2, 3) in the arrangement is provided with a cover (4, 5) which in the disconnected condition of the connector protects the interfaces in the light path (1a, 1b) and which during mating of the contact parts (2, 3) for mutual coupling between these, is adapted to be displaced in order that the interfaces be exposed and that a continuous light path is established through the connector. Each cover (4, 5) has a wiper element (6a, 6b) adapted to clean the corresponding interface when the cover is displaced. Preferably each connector part has a separate fiber holder which suitably is suspended in a movable manner. The location of the light path in the side-wall of the connector leads to particularly good possibilities for protection and cleaning. A main use of the arrangement is for detachable connections and for interconnections in fiber optic systems, in particular in regions with contamination, for example for military applications and on offshore installations.

Description

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Fiber Optic Connector.
This invention relates to a fiber optic connector wnich in particular is intended for applications where the probabi-lity of contamination is high, for example in mili-tary equip-ment or in offshore and underwater installations and certain industries. A simple connecting operation and good protection in disconnected condition is important in such applications.
The practical use of fiber optic systems requires detach-able contacts for termination at a transmitter and a receiver.
In some applications there are also employed fiber optic con-nectors for joining already terminated cable lengths. A long transmission di~tance and a safe signal transmission requir~ a minimum of transmission losses in the connectors.
The losses in fiber optic connectors are inter alia deter-mined by the positioning accuracy and possible contaminations in the connector. Connectors having lenses which collimate and focus the light, require a lower longitudinal and transver sal positioning accuracy, as for example described in EPC
patent application of Publication No. 0057794. Such a lens system will also reduce the sensitivity of the connector with respect to foreign particles in the light path. Anyhow, fiber optic connectors will often be subject to contamination and thereby increased transmission losses in the transmission.
In EPC Patent Application Publication 0024989 there are described fiber optic connectors having movable covers which serve to protect the fiber ends and otherwise the interior of the connector parts. This known arrangement is based upon a terminating axial displacement of the optical fibers in the connector so that these are brought into mutual abutment for the finished interconnection. Thus, the arrangement does not make possible any cleaning of the optical interfaces on the fiber ends in connection with the coupling operation.
It is a purpose of this invention to provide an improved fiber optic connector which to a substantial degree reduces the problems discussed above. Thus, on the background of the state of the art the invention takes as a starting point a i ~
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fiber optic connector comprising two mating eonneetor parts eaeh being provided with a cover for pro-tection in the discon-nected eondition of the connector, the mating movement of the connector parts for eoupling these together causing movement of the covers so that there may be formed a con-tinuous light path -through the connector. What is novel and specific in the connector according -to the invention in -the firs-t place eon-sists therein that the optical light path is permanently extended to an interfaee on eaeh eonneetor part, -that the interfaces of the connector par~s are adapted to slide against each other during the mating movement and that eaeh eover has a wiper ele-ment adapted to clean the ad]aeen-t interfaee during movement of the cover.
With this solution the eonneetor will be self-cleaning at the same time as it is proteeted against contamination when disconnected. Thus, when the connector is disconnected or de-taehed, a protective eover is loeated in front of the trans-mission path where it is penetrating an interfaee in eaeh eon-neetor part. When the eonneetor is eonneeted, the eovers on both conneetor parts are displaeed and this movement eauses a wiping aetion on the interface of the fiber end or lens eon-eerned, whieh is incorporated in the optieal light or signal path in the eonneetor. The eovers are preferably spring biassed and therefore are automatically brought into the proper plaee when the eonneetor is diseonneeted. It is also possible, however, to let the design be based upon a manual retraetion of the eovers when the eonneetor is diseonneeted. Moreover, the eovers may be provided with return means whieh make it possible to eheek the fibers when the eonneetor is diseonneeted.
In the strueture deseribed here the light path is running in sueh a way in the conneetor that the direetion of movement of eaeh eover eoineides with the direetion of movement when mating the eontaet parts. Thus, the direetion of movement is essen-tially transverse to and preferably normal to the light path in the region adjaeent the interfaees. In a praetieal embodimen-t -the light path interfaee lies in a side-wall of the f~

connector par-t concerned, running parallel to the mating direc--tion or substantially coincident with the longitudinal direction of the connector and thereby with the main direction of -the fiber op-tic cables or wires on which the connector parts are mounted.
As a wiper elemen-t -there is preferably used a rubber profile or the like. This may be mounted in a suitable recess in the cover. Instead of rubber as the material of the wiper element, a suitable type of plastic material or another suitable material may be used.
A substantial advantage of the solution s-tated here consists therein that the protective covers are automatically dis-placed and removed when -the connector parts shall be connected, and at the same time results in a wiping action which will remove possible contaminations which might have reached the interfaces of the light path in the connector parts.
In connection with the solution discussed above there has also been developed fiber holders cn which one surface consti-tutes said interface, these fiber holders preferably havi,ng a certain limited degree of movability.
The invention may be summarized as a fiber optic con-nector comprising two cooperating connector parts each being provided wi-th an associated cover for protection in a disconnected condi-tion of the connector, whereby the mating of the connector parts for mutual coupling therebetween causes movement of said covers so that there is established at least one continuous ~, ~S4~
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optical light path through the connector, wherein: said at least one opti.cal light path includes a Eirst optica] fiber permanently extended to a surface on a firs-t one of said connector parts and a second optical fiber permanently extended to a surface of a second one of said connector parts; said surfaces on said con-nector parts are arranged to slide against each other during movement to couple said connec-tor parts; said covers are arranged to slide respectively over the surfaces of their associated con-nector parts during said movement; and each said cover has a wiper element adapted to clean a tip of the optical fiber whichextends to the surface of the associated connector part when said cover slides.
The invention will now be described in greater detail with reference to the accompanyi.ng drawings, in which:
Figure 1 schematically and simplified shows the prin-ciple of the arrangement according to the invention, seen in longitudinal section, Figure 2 shows with a similar simplification and in longitudinal section, an arrangement with lenses for collimating/-focusing of the light signal, Figures 3a-d show the arrangement of Figure 2 partly in longitudinal section and partly in cross-section, with the connector parts disconnected from each other, Figure 4 shows an embodiment including mi:rrors or prisms, Figures 5 and 6 show two modifications of the arrange--3b-ment of Figure 2, Figures 7a and 7b schematically and simplified show a fiber holder seen from the interface and in cross-section, respectively, ~2~

Figure 8 shows a somewha-t simplified cross-section of an arrangement with fiber holders as shown in principle on Figures 7a and 7b~ in a mated position, Figure ~ shows the arrangement of Yigure 8 in longitudinal section, Figures 1Oa and 1Ob show one connector part (the female part) in the arrangement of Figures 8 and 9, disconnected and in longitudinal, respec-tively cross-section, also showing some ~urther details, Figures 11a and 11b show in longitudinal and cross-sec-tion, respectively, the other connector part (the male part~
in the arrangement of Figures 8 and 9, in disconnected position.
In Figure 1 there are shown two connector parts 2 and 3 oE
which ~he former may be regarded as a male connector and the latter a female connector. The connec-tor parts are shown in their connected position, the mating movement having taken place in a horizontal direction in the figure, for example by displacement of the female connector 2 from the right towards the left of the figure. In both connector parts there are shown two through-going optical fibers 1a and 1b considered to be extended out of the female connector 3 towards the ieft into an associated cable or wire. From the male connector 2 the fibers are considered to be extended out to the right, for example to a fiber optic cable connected -to the male connector.
During a coupling operation the upper surface or side-wall on the end portion of connec-tor part 2 slides on a corres-ponding lower surface (side-wall) on the end por-tion of connec-tor part 3 until the fiber ends are positioned directly opposite each other in points 1Oa and 10b. Accordingly, in this embo-diment the fibers 1a and 1b are deflected substantially at a right angle from their general direction towards their respec-tive interfaces being in engagement with each other in points 10a and 1Ob.
As known per se connector parts 2 and 3 may be made of metal and designed with an inner cavity filled with a suitable liquid which surrounds the optical fibers 1a and 1b. It is obvious that such a connector may be intended for one, two or ~54~3~

a higher number of optical fibers.
Further, Figure 1 shows a protective cover 4 for the male connec-tor part 2 and a protective cover 5 for the female connec--tor part 3. I'hus, in the position shown in Figure 1, the cover 4 is retrac-ted on the male connec-tor 2 in a right-hand direc-tion by -the ac-tion of the end of the female connector 3 in order that the flber ends may be exposed on the surface of the male connector 2. In disconnec-ted position -the cover 4 is adapted -to enclose the outer or le~t-hand end of the male connector 2 as shown in this figure, so -tha-t the fiber ends are covered and protected. This retraction of cover 4 takes place automatically by means of a helical spring which is not shown in the figure.
In a manner similar to cover 4 also cover 5 is displace-able under the action of a compressive spring which seeks to force the cover 5 to the right in the figures. However, ln the mated condition shown the cover 5 is pushed back from the end portion of the female connector 3 by means of the end of the male connector 2.
An essential feature of the arrangement shown consists therein that the covers 4 and 5 are provided with a rubber pro-file element 6a and 6b, respectively, which constitutes a wiper element adapted to clean the contact surfaces when -the covers are moved. The location of the rubber elements on the covers will also contribute to the formation of a tight closure over the ends of the connector parts and in particular the contac-t portions thereof in their disconnected condition.
The protective covers are made with dimensions and a design conforming to the respective cooperating connector parts, and during mating in order to establish contact there will be a natural movement which provides for the desired wiping and cleaning. Positioning of the interfaces or the ends of the optical fibers is obtained by having the connector parts accu-rately machined to fit into each other with the proper tolerances so as to obtain low losses.
Figure 2 illustrates a similar arrangement as the one in ~5~

Figure 1, but having lenses inserted for collimating, respec-tively focusing the light signal. Thus, for the optical fiber 11a in Figure 2 -there is mounted a lens consisting of two halves 17a~17b each mounted to its connector part, i.e.
male connector 12 and female connec-tor 13, respectively. The surfaces to be cleaned in the light path are in -this embodimen-t the side-wall facing downwards on lens member 17b and the side-wall facing upwards on lens member 17a. A rubber element 16a on cover 14 therefore serves to clean the interface on lens member 17a whereas a rubber element 16b on cover 15 serves to clean the interface on lens member 17b.
The lenses employed rnay for example be of the type having a graded index of refraction and be ng sold by Nippon Sheet Glass ~ompany under the designation~SELFOC. However, such a connector may also be designed for other types of lenses. The advantage with a design with lenses is -that the positioning requirements in the longitudinal and the transverse direction are less severe.
For a more detailed explanation of the embodiment of Figure

2, Figures 3a, 3b, 3c and 3d show the two connector parts in dis-connected condition. Thus, Figure 3a shows the female connec-tor 13 with the protective cover 15 in position so as to cover the interfaces on the pair of lenses. The same also is apparent from the cross-section in Figure 3b. In a corresponding manner Figure 3c shows a cross-section and Figure 3d a longitudinal section through the male connector 12 with protective cover 14 in closed position over the lens surfaces.
Figure 4 shows an embodiment of the arrangement based upon mirrors or prisms, inter alia for the purpose of ma~ing possible a higher number of connections or optical fibers in the connec-tor. The arrangement of Figure 4 may either be circular or rec-tangular, possibly a square arrangement in which a male connec-tor 22 is adapted to be moved centrally into a female connec-tor 23. The cover 24 of the male connector is provided with a rubber element 26a whereas -the cover 25 of the female connector is provided with a rubber element 26b. There are shown two signal or light paths through the connector, of which the lower ~ ~a~D ~, ~

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path comprises optical fibers 21b, a lens 27b in the male connector 22 and ano~her lens 27bb in the female connector 23, associated prisms 28b an~ 28bb respectively, as well as an optically transparent material 29b and 29bb respectively, filling the space between both prisms. Thus, in this embodi-ment it is the inter-engaging interfaces or side-walls of the filling 29b and 29bb, respectively, which is subjected to the self-cleaning effect by means of the rubber element 26b and 26a, respectively, when the connector part is disconnected and connected, respec-tively.
The retraction of covers 24 and 25 when disconnecting the connector in Figure 4, takes place automatically by means of helical spring 102, 101 respectively, which exert a pushing force on the respective covers. Spring 101 which seeks to push cover 25 to the right in the figure is therefore in engagement (not shown~ against a part of the female connector 23 to the left outside the figure. In a corresponding manner spring 102 pushes in the opposite direction on cover 24.
As in the embodiments shown in Figures 1, 2 and 3 the interfaces in the embodiment of Figure 4 may be regarded as lying in a side-wall of the respective connector parts 22 and 23. These side-walls run parallel to the direction of movement of the connector parts when mated, and during disconnection thereof, respectively. In the examples shown this direction of movement is substantially the same direction as the main direction or longitudinal direction of the connector itself and the cables or wires connected thereto.
Figures 5 and 6 illustrate particular modifications of the arrangement of Figure 2, with a design of the cover which makes it possible to measure the light transmission in the adjoining fiber cable when the connector is disconnected. In Figure 5 there is shown a connector part 43 with optical fibers 41a and 41b with associated lens parts 47a and 47b, respectively.
A cover 45 in similarity with the embodiment of Figure 2 has a rubber element 46 for wiping the interfaces on lenses 47a and 47b. Besides, on cover 45 there is mounted a prism 5~

49 which wi-th its reflecting surfaces provides for the coupliny of the optical fiber 41a directly hack to the op~ical fiber 41b so that the op-tical signal is sent back through the cable being connected to connector part 43.
In -the embodiment of Figure 6 there is shown a connec-tor part 53 with optical fibers 51a and 51b with associated lens members 57a and 57b. In this case cover 55 is provided with two lens members 57a and 57bb adapted to cooperate with the two first mentioned ler.s members and besides being mutually interconnected through an optical fiber loop 59 so that also here there is obtained a retransmission of the optical signal from fiber 51a to fiber 51b when the cover 55 is in its protec-tive position.
The embodiments of Figures 5 and 7 involve a particularly advantageous possibility for checkinq the cable and terminal equipment when there is employed a connector according to -the present invention. Such a checking or monitoring possibility is not previously known from the literature and is particularly incomplicated with the proposed location of the ligh-t path in the side-walls of the connector. In consequence of the above described cleaning effect obtained by means of rubber elements on the covers, for example rubber elements 46 and 56 on covers 45 and 55, respectively, as shown in Figure 5 and Figure 6, respectively, there exist very good conditions for useful and correct measurementSfor checking associated fiber cables and terminal equipment in connection with the employment of fiber optic connectors according to the invention.
On the remaining E'igures 7-11 there is shown a structure based upon the same principle as above, but with certain im-portant details further developed. This in particular applies to a specific fiber holder on each connector part, whereby a surface of the fiber holder constitutes said interface, which fiber holder serves to mount the optical fiber or fibers in-corporated in the arrangement, possibly a lens or lenses and a protective glass or windows.
Thus, these fiber holders are located in the side-wall of -the connector parts. According to what has been described ~J~ ~ 4 ~ ~

above also these fiber holders are protected each by a separate cover in disconllected condition, whereas during mu-tual coupliny of the connector parts they are exposed and form a continuous light path throuyh the connector. According to the same prin-ciple as above the covers and/or the connector parts may also here be provided with wiper elements which clean the fiber holders when coupling is effected.
Moreover, -the fiber holders may be provided with lenses which collimate and focus the light from and to the fiber ends. Such lenses reduce the requirement as to positioning accuracy and makes it possible to employ a protective glass.
Another important fea-ture of the embodiment described here has to do with the positioning of the connector parts or more specifically of the fiber holders in relation to each other.
This is obtained by means of guide pins which for example from the fiber holder of the female connector are automatically pres-sed down into holes in the male connector fiber holder when the same has an approximately correct position. One or both fiber holders, for example the fiber holder in the female connector, is suspended in a flexible or movable manner, for example under spring bias, and thereby makes possible an exact positioning with respect to the cooperating fiber holder.
Disconnection may take place upon having lifted the guide pins out of the corresponding holes by means of a lifting mechanism. The lifting mechanism is activated with a release arm which is incorporated in one of the connector parts, for example in the male part.
While Figures 7a and 7b illustrate a fiber holder separa-tely, the remaining Figures 8 - 11 are related to the same structure seen in various stages of mating and disconnecting, in longitudinal and cross-sections, respectively, as stated more closely in the list of figures above.
In Figures 8 and 9 there are shown two connector parts 210 and 211 of which the former may be regarded as a female connector and the latter a male connector. The connector parts are shown as mutually coupled, the mating movement having taken place in a hori~ontal direction in Figure 9, ~ ~s~

for example by having displaced the male connector 211 from -the right towards the left in the figure. In Figure 8 the same connector parts are shown in cross-section. Thus, Figure 8 shows a continuous light path through a fiber holder 201a, fibers 206a, lenses 204a, protective glass 203a and an inter-face 202. Moreover, in the male connector there are in a similar way a protective glass 203b, lenses 204b and optical fibers 206b in a fiber holder 201b.
The op-tical fibers illustrated con-tinue into cables 100 and 110, respectively, which may be terminated in -the connector parts as shown in Figure 1Ob with respect to the female connec-tor and in Figure 11a with respect to the male connector.
During coupling the outward surface 202 on the male fiber holder 201b slides against the corresponding surface on the female fiber holder 201a. It is obvious that these surfaces correspond to the previously mentioned interfaces or side-walls. The movement goes on until the guide pins 207 are pressed into corresponding holes 105 (Figure 7b) in the fiber holder of the male connector.
Figures 7a and 7b schematically show a fiber holder 101 with associated holes 105 for a guide pin, holes 104 for lenses and fibers and a recess 103 for protective glass. The fiber holders may be made for the desired number of fibers by changing the number of lenses 104. As apparent from Figure 7b this embodiment is intended for six fibers.
An exact positioning between the fiber holders in both connector parts (Figures 8 and 9) may be obtained because the female fiber holder 201a is resiliently suspended and has a spring bias. Such springs 214 and 215 are shown in Figures 1Oa and 1Ob. Similarily the guide pins 207 are forced down by separate springs 216 and 217. The described resiliency or movabili'cy of one or possibly both fiber holders, which may also be obtained in other ways, reduces the requirement as to tolerances and accuracy of the remaining portions of the connector.
When the guide pins are depressed into the male connector the connec-tor parts are latched with respect to each other.

Disconnection takes place by operating a lifting mechanism 208 which lifts the guide pins 207 out of the holes in the male fiber holder 201b and the connec-tor parts may be with-drawn from each other. The lifting mechanism is elevated by means of a release arm 212.
Similar to what is explained with reference to Figures 1 - 6, the structure of Fiyures 8 - 11 is designed so that -the protec-tive covers 209a and 209b, respectively, for the female connec-tor and the male connector, respectively, is automatically put in-to position in front of their respective fiber ho]ders 201a, 201b when the connector is disconnected. Automa-tic re-turn of the covers may be obtained for example by means of springs 213. The au~omatic operation of the covers is possible because the fiber holders are located in the side-walls of the la-teral connector and because of the simple design of the connector otherwise.
The desi~ln and ~oupling principle of the fiber connector also makes it possible in the embodiments of Figures 8 - 11 to provide the covers 209a, 209b and the connector parts 210, 211 with wiper elements 219a, 219b and 21~a, 218b, respecti-vely, for cleaning the interface 202 of the fiber holders including the protective glasses 203a, 203b. The wiper ele-ments reduce the probability of losses due to contaminations.
The elements may be located in suitable grooves and may be made of leather, rubber or a plastic material. The movement of the connector parts when brought into engagement with each other will cause the wiper elements to be moved over the de-scribed interfaces on the male connector and the female connec-tor, respectively.
The protective cover 209a (Figure 1Oa~ for the female connector may be provided with return means 220 in front of the protective window 203a in order that the light transmission in the fibers may be checked when the connector is disconnected.
The return means 220 may be a prism or a material having a de-fuse reflec-tion. The protective cover 209b for the male con-nector may also have similar means in order to obtain a possi-bility of monitoring the light transmission in the fibers ex-tended to the male connector, when in a disconnected condi-tion.
The number of connections or optical fibers changes inthe various embodiments shown in the figures of drawings.
It is obvious that in principle a:Ll the embodiments being shown more or less schematically, may be modiEied so as to make possible the coupling of one or more con-tinuous light paths~therethrough.

Claims (13)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A fiber optic connector comprising two cooperating con-nector parts each being provided with an associated cover for protection in a disconnected condition of the connector, whereby the mating of the connector parts for mutual coupling there-between causes movement of said covers so that there is estab-lished at least one continuous optical light path through the connector, wherein: said at least one optical light path includes a first optical fiber permanently extended to a surface on a first one of said connector parts and a second optical fiber per-manetly extended to a surface of a second one of said connector parts; said surfaces on said connector parts are arranged to slide against each other during movement to couple said connector parts;
said covers are arranged to slide respectively over the surfaces of their associated connector parts during said movement; and each said cover has a wiper element adapted to clean a tip of the optical fiber which extends to the surface of the associated connector part when said cover slides.

2. The connector claimed in claim 1, wherein the wiper element is a rubber member.

3. The connector according to claim 1, wherein there are at least two said continuous optical light paths, and wherein each cover is provided with return means for, in the disconnected condition of the connector with the cover in a protective position, retransmitting an optical signal in one of the light paths back through another of the light paths.

4. The connector according to claim 3, wherein the re-turn means comprises a reflector.

5. The connector according to claim 4, wherein the reflec-tor is a prism.

6. The connector according to claim 3, wherein the re-turn means comprises an optical fiber loop.

7. The connector according to claim 1, wherein each connector part includes a fiber holder mounting the respective said optical fiber and defining the respective surface to which the optical fiber extends.

8. The connector according to claim 7, wherein the fiber holder in at least one of the connector parts is suspended with a certain limited movability, under bias for an exact mutual posit-ioning of said surfaces and said light paths in the mated con-dition.

9. The connector according to claim 8, wherein such posi-tioning is achieved by means of guide pins in one of the fiber holders adapted to be automatically depressed into corresponding holes in the other fiber holder.

10. The connector according to claim 9, wherein the guide pins are adapted to be pressed out of the holes in the other fiber holder by means of a lifting mechanism activated by a release arm.

11. The connector claimed in claim 7, wherein at least one of the fiber holders further mounts at least one lens.

12. The connector claimed in claim 7, wherein at least one of the fiber holders further mounts a protective glass.

13. The connector claimed in claim 7, wherein at least one of the fiber holders further mounts a window.