Locking mechanism for a light pipe joint

The invention relates to a fiber optic connector assembly, and more particularly to a connector lock mechanism for making a connection between a panel or mounting plate and a circuit board.

It is relatively common in the electronics industry to transmit signals over optical fiber because of the many advantages that light transmission has over the transmission of electrical signals. These are: very high speed of signal transmission and the insensitivity of light signals to electric and magnetic fields. A common example of high-speed data transmission is the transmission between printed circuit boards, and it is often desirable to have both an electrical and an optical connection between the boards. Such a connection often occurs between the mounting plate and the secondary plates.

The optical fiber cable is usually made up of an inner core surrounded by a sheath, reinforcement fibers arranged around it, and protective plastic insulation. The core transmits all or most of the light and is usually made of glass or plastic, with a core diameter of up to eight micrometers. The sheath surrounding the core is usually made of plastic or glass and serves to keep the light inside the inner core due to the specially selected and different reflectance of the core and sheath, the outer diameter of the sheath being from about twenty to one hundred and twenty-five micrometers. Very small inside diameter inner light-transmitting core means that great accuracy is needed when coupling the two optical fibers together. This is achieved by guiding the core and sheath through the opening of the fine-cut bushing and securing it therein by bonding, the light guide protruding from the tip of the sleeve, which is then finely polished so that the light guide ends flush with the sleeve. The next sleeve is inserted into a precisely made sleeve, which accurately centers and positions the sleeve. In this case, the sleeve of the second optical fiber cable can be introduced from the other end of this precisely manufactured sleeve until the ends of the two sleeves, with which the fibers to be joined, come into exactly centered contact with each other. It is also important to ensure that the gap between the ends of the optical fibers to be joined is as small as possible and does not change, which requires the sleeves to be pressed together. This is achieved by means of springs mounted in the fiber optic connector and resting on the sleeve. Such a spring also absorbs the axial changes in the position of the ends of the sleeves. In order to be able to accurately center the sleeves in the sleeve, it is necessary to allow the sleeves to float in relation to the joint, which is obtained for example by leaving a clearance between the sleeve and the housing.

One of the difficulties in making an optical connection between the plates is due to inaccurate spacing of the plates, which can be the case, for example, in a junction connector where a number of adjacent optical and / or electrical connectors are arranged on one plate and are simultaneously inserted into the mating connectors. connectors on the mounting plate. Electrical connectors can be easily constructed to accommodate two or three millimeter alignment differences simply by making the socket and mating pin or solder tip long enough. In the case of optical connectors, however, the problem is that inaccuracies in alignment are eliminated by springs, as mentioned above, which can generate both a very high compressive force and an insufficient compressive force. This changing spring force is undesirable due to the potentially high loads on the mounting plate and the unmanageable shock forces of the bushings. Additionally, it is desirable to avoid the absorption of spring forces by the plates, as this causes them to warp and requires a stronger and structurally more costly support for them.

In an article titled Compact and Self-Retentive Multi-Ferrule Optical Back Panel Connector published in Journal of Light Wave Technology, Vol. 10, No. 10, October 1992, a backplate mounted socket and a PCB mounted plug intended for use were disclosed. connecting them together optically. In this case, the plug has a hooking mechanism for hooking inside the socket housing. The plug also has a latch release that disconnects the plug and socket from the outer socket housing connected to the backplate.

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This solution provides a means for relieving the forces of the springs connecting to the plates and allows the plug and socket to move axially with respect to the backplate, which obviates the axial tolerances. One problem with this solution, however, is that the backplate socket can have a significant number of optical connectors, the fiber optic cables extending from the rear of the backplate socket are relatively heavy and stiff, thereby stressing the socket.

However, the plug must be able to slide inside the outer casing, which means that the mounting of the socket in the outer casing must allow some play. Thus, not only the attachment of the socket to the backplate has been weakened by the requirement for slip, but the sliding of the socket inside the outer casing has been made more difficult due to the increased frictional force and tilting of the socket inside the outer casing due to loading by the fiber optic cables.

EP 430 107 discloses an optical connector that can be engaged or disengaged by a simple plugging-in-and-out operation without applying force to the sleeve to other components. The optical connector comprises a first housing, a second housing, a third housing slidably held in the second housing, a first coupling mechanism between the second and third housing for engaging the two housings when the first and third housings are not engaged, a second coupling mechanism between the first and third housings for engaging these two housings. two housings when the first housing is coupled to the second and third housings. The connector further comprises a first release member for the first housing to release the first clutch mechanism when the third housing is engaged with the first housing and a second release member for the second housing to release the second housing mechanism when the second housing is engaged with the third housing or the first housing is decoupled from the second and third housing. Moreover, in order for this optical connector to be successfully used for a plug connector with the smallest possible dimensions and the highest possible packing density, a new design of the floating connector, a new design of the sliding support sleeve, a reliable optical connection mechanism of the plug, a reliable construction for inserting a plug or a socket are also provided. optics, connector socket that can be cleaned and replaced, etc.

An optical fiber connector assembly for connecting the optical path of optical fibers, according to the invention, comprises a socket with at least one side of an optical fiber supporting sleeve disposed therein on at least one side thereof. It also includes a plug comprised of an outer casing, an inner plug body with at least one spring connection member mounted therein, and a bushing for supporting a second optical fiber. The socket with the plug are snap-connected by means of catch elements located in the socket housing and on the plug body. The optical fiber connector assembly according to the invention is characterized in that its plug includes expansion means that enable the plug to be inserted into the socket, and the socket includes expansion decoupling means. The plug expanding elements are resilient resilient expanding lances resting on the forward-facing sill of the outer plug housing. The socket decoupling element is the inner surface of the ribs situated on the inner surface of the socket housing and bending the elastic expansion lances from the threshold of the outer housing.

Each optical fiber support bush is mounted in a separate inner plug body. The inner plug body is mounted coaxially slidably within the outer casing cavity of the plug and the outer surface of the inner plug body contacts the inner surface of the cavity. On the front edge of the outer plug housing there is a bridge projecting into the cavity, on which bridge the engagement lugs of the inner plug body are supported.

Preferably, the resilient expansion lances are integral with the plug body insert.

Preferably, the expanding lances protrude obliquely outward into the bore of the plug housing.

Preferably, the expanding lances are biased by thrust decoupling means located in the front part of the socket.

The catch elements of the socket are resilient catch arms directed to the front and having catch teeth on the free end, cooperating with the catch bosses of the plug in the form of ribs situated inside the body / plug.

Preferably, the connector assembly includes at least one pair of gripping arms per one plug bushing.

Preferably, the plug housing has cam members with cam surfaces to which the wings of the resilient hooking arms are interconnected.

Preferably, the plug has at least one pair of cam members separated by a chamber, the cam members located axially on the top or bottom of the plug housing.

Preferably, at least one pair of cam members is provided on the upper side and on the opposite lower side of the plug housing.

The advantage of the invention is that its structure allows to eliminate the misalignment of the coaxiality between the socket and the plug, and in addition, the connection between them is permanent and immovable. It does not exert significant forces on the components to which it is attached or inside the joint. The hooking mechanism of the fiber optic connector is reliable, can be easily coupled and disconnected without the need for tools. The fiber optic connector of the invention is particularly suitable for use in a manifold connection system comprised of both fiber optic connectors and electrical connectors, in which the fiber optic connectors are able to absorb the axial tolerance necessary for the electrical connector.

The subject matter of the invention in an embodiment is reproduced in the drawing, in which Fig. 1 shows an optical fiber connector known from the prior art in an axonometric view; Fig. 2 is an axonometric exploded view of the connector plug of Fig. 1; Figure 3 is an axonometric exploded view of the connector plug body of Figure 2; Fig. 4 shows the socket of the connector of Fig. 1 in an exploded state in an axonometric view; Fig. 5 is a cross-sectional view of the socket of Figs. 1 and 4; fig. 6 the socket of the optical fiber connector assembly according to the invention, in a position just prior to insertion of the plug therein, in cross-section; Fig. 7 is an axonometric view of a single plug in an exploded state according to the invention; Fig. 8 is an axonometric view of the front hook profile of the plug housing of Fig. 7; Figures 9 to 13 show the steps of latching the socket and plug, while Fig. 11 - the moment of releasing the expanding elements; fig. 14 to 17 show the steps of disconnecting the plug and socket; Fig. 18 is a cross-sectional view of another embodiment of a fiber optic connector; Figure 19 is a front top view of a hybrid connector housing including both optical and electrical connectors; Figure 20 is a bottom view of the housing of Figure 19 and Figure 21 is a side view of the housing of Figure 19.

FIG. 1 shows a commercially available optical fiber plug 2 which is inserted into and snap-fitted to a socket 4. This known optical fiber plug 2 is composed of an inner plug body 6 and an outer plug housing 8.

The plug 2 will now be described in more detail with reference to Figs. 2 and 3. The inner plug body 6 of Fig. 2 is shown in Fig. 3 in a disassembled state to show the insulating housing body 10, bushing 12, helical spring 14, insulating tube 16. and an inner body 18. The casing body 10 has an inner chamber 20 for receiving the sleeve 12, and the rear part of the inner chamber 20 is contoured to receive the front end 22 of the inner body 18. The ceramic sleeve 12 is free to move inside the body of the insulating casing 10, biasing the spring 14 between the piston portion 24 of the sleeve 12 and the outer flange 26 of the inner body 18. The optical fiber 28 slides through the inner body 18, insulating tube 16 and helical spring 14 into its position end in sleeve 12, the tube 16 and the inner body 18 being inserted into the body of the insulating casing 10 to maintain the tension of the spring 14.

The housing body 10 has upper and lower surfaces 30 and two side surfaces 32. It also has two bevelled surfaces 34 providing the insulating casing body 10 with proper alignment with the outer plug housing 8, as will be described in more detail hereinafter. A portion of the upper and lower surfaces 30 of the housing body 10 has a recess 36 that extends from front to rear into a transverse rib 38, followed by a second surface recess 40, the posterior side sloping surface 42 of which leads upward to the protruding stop surface 44. It should be noted that that bottom page

173 558 of housing body 10 is identical to the top surface (only one such surface is shown in FIG. 3).

Figure 2 shows the outer plug housing 8 in more detail, which has an inner cavity 50 for slidably insertion of the housing body 10 from the rear until it is locked. The chamber 50 has bevelled surfaces 52, corresponding to beveled surfaces 34 for properly positioning the housing body 10 in the outer housing 8. The upper and lower walls of the outer housing 8 are provided with catch holes 54 which are close to the front face 56. The openings 54 each have two side walls 58 connected by upper and lower bridges 60. Side walls 58 extend rearward from front face 56 adjacent to cam surfaces 62 extending obliquely backward to upper surface 64 of side walls 58 of outer casing 8. A recess is provided on the inner surface of side walls 58 having one sloping edge 66 and the other horizontal edge 68. At the rear edge of the opening 54, a cutout 70 is made, which forms a stop for the outer casing 8. Finally, the casing 8 has a pilot projection 72 on one side for its proper positioning in the seat 4.

The plug inner body 6 is placed in the rear part of the plug outer casing 8 by sliding it into the fully locked position as shown in Fig. 1. The protruding stop surface 44 of the inner body 6 is snapped into the recess 70 of the outer casing 8 which prevents the plug inner body 6 from being pulled out. from the housing 8. The body 6 is however able to move forward in the outer casing 8 of the plug until the transverse rib 38 rests against the rear edge of the bridge 60.

The socket 4 will now be described in greater detail with reference to Figures 14 and 5. It is composed of two identical socket halves 80 having flanges 82 which can be pressed together and joined together by means of glue or ultrasonic welding. The receptacle 4 further comprises two identical detent members 84 inside which a centering sleeve 85 of the optical fiber is seated. The sleeve 85 is inserted into openings 86 from the rear of the engaging members 84 and is held within the cylindrical portions 88 of these engaging members 84 by shoulders 90 at their ends as best seen in Figures 4 and 5. The engaging members 84 further have arms. striker 91 with striker 92 having wings 94 on the sides. One of the half of the socket 80 can be clamped with a metal spring clip 95, by which the socket 4 can be secured to the mounting plate 100. The socket 4 is fixed to the mounting plate 100 between the flanges 82 and the locking lance 96 of the clamp 95. Finally, both identical halves are identical. 80 of the jacks have a pilot slot 98 for receiving the pilot projection 72 of the plug 2.

The connection and disconnection of plug 2 and socket 4 is as follows. The plug 2 is inserted into the cavity 99 (Fig. 5) of the socket 4 so that the sleeve 12 of the plug 2 slides into the centering sleeve 85 of the socket 4. It should be noted that the wings 94 (Fig. 4) on the catch arms g of the socket 4 are so wide as the cam surfaces 62 (Fig. 2) of the outer housing 8 of the plug, but narrower than the inner surfaces 71 (Fig. 1) on the side walls 58 (Fig. 2) of the housing 8. Therefore, when the plug 2 is inserted into the socket 4, the wings 94 ride on the cam surfaces 62 then on the upper surfaces 64 of the side walls 58. Further insertion of the plug 2 causes the wings 94 to slide down the sloping edge 66 to a resting position at the horizontal edge 68 (Fig. 2). This aligns the detent protrusion 92 of the socket 4 behind the transverse rib 38 on the housing body 10. Due to the action of the spring 14 on the front face of the sleeve 12, the plug inner body 6, when the plug 2 snaps into the socket 4, is always positioned in such a position that the catch 92 rests on the transverse rib 38. The pulling force exerted on the inner body 18 the plug 2 or the fiber optic cable 7 will not pull the plug 2 out of the socket 4 due to the latching engagement of the tab 92 with the transverse rib 38.

To pull the plug 2 out of the socket 4, the outer casing 8 of the plug 2 has to be moved rearward until the front edge of the transverse rib 38 rests against the rear edge of the sternum 60 (Fig. 2) causing the wings 94 (Fig. 4) to enter. upwards along the sloping edge 66 and will be on the upper surface 64 (Fig. 2) of the side walls 58. This raises the catch projection 92, and further rearward movement of the plug outer casing 8 pulls the entire plug 2 out.

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Similar but significantly improved to the above-described fiber optic connector assembly has been used on slave boards, especially in combination with electrical connectors having pins and mating sockets therewith. More specifically, the inventors have proposed that a fiber optic connector similar to that shown in Figs. 1-3 be mounted on the slave next to a female connector similar to that described in European Patent Application No. EP-A-0 422 785. A socket similar to that shown in Figs. 4-5 could be attached to the mounting plate next to the head also described in the above-mentioned European patent application. Although the combination of fiber optic connectors and connector system described in the above-mentioned European patent application is highly desirable, this combination introduces new complications.

A requirement for such a system as described in the above-mentioned European patent application is that there must be an axial tolerance between the mating joints of, for example, 2.5 mm. Thus, the fiber optic connector described above with reference to Figs. 1-5 is unusable because the connector would place a considerable strain on the backplane and slave. For example, if a plug connector similar to that of Fig. 2 would be mounted directly on the slave plate, and the electrical plug and the optical fiber plug would be inserted into the head mating with the electrical plug and into the optical fiber socket, respectively, and would be brought into a coupling in which the optical fiber plug is fully engaged (i.e. to the position where the tabs 92 are located behind the transverse rib 38), it might still be necessary in view of the tolerances described, displacement of the slave plate a further 2.5 mm. Although the forward movement of the slave plate would be possible due to the helical spring 14, the additional force acting on the sleeve due to the additional deflection of the helical spring would exceed the strength of the slave and mounting plate as they bear the full axial load.

Figure 6 shows a fiber optic connector assembly suitable for use in conjunction with electrical connectors, so-called hybrid connectors. It should be noted that the plug mounted on the left side of the mounting plate may be identical and is in fact shown to be identical to the known plug of Fig. 1. However, the socket is slightly different than that shown in Fig. 1 and therefore has the reference numeral 204. However, the socket half 80 and the inner detent member 84 are substantially the same as described above with respect to Figs. 1-5.

Figures 6 and 7 show a plug 102 having similar characteristics to plug 2 with an outer casing 104 attached to a secondary printed circuit board 101 and with an inner plug body 106 slidably disposed within a cavity 111 of the outer casing 104. The inner body 106 has an insert 109. (Fig. 7) which includes an inner chamber 110 in which a helical spring 112 is mounted to push the piston 114. Attached to the piston 114 is a sleeve 116 that has a thin central hole for the optical fiber.

The insert 109 shown in Fig. 7 has a skirt 118 surrounding the sleeve 116. As with the plug inner body 6 of Fig. 2, the plug inner body 106 also has tabs 128 behind which a cutout 126 is formed. Instead of a protruding stop surface 44 shown in Fig. 1, plug body 106 has resilient expanding lances 150 which, for example, may be clamped around insert housing 109 or may be integral with inner body 106.

The outer housing 104 of the plug 102 shown in FIG. 8 includes cam members 120 with a chamfered front cam surface 124, a planar top surface 125 and a chamfered entrainment rear surface 122 and a bottom surface 121. There are two cam members 120 separated by an aperture 127. At the front end of the outer housing 104 there is a bridge portion 131 that connects cam members 120. The bridge portion 131 also serves to retain the front latching shoulder 128 of the plug body 106 that abuts against the bridge 131 after the body 106 is slid into the outer housing 104.

The inner body 106 shown in Fig. 6 has an outer surface 151 shaped like the inner surface 153 of the chamber 111 so that the inner body 106 is

173 558 slidably held within chamber 111. Resilient spreader lances 150, projecting obliquely rearward, engage shoulders 152 of outer casing 104. Inner plug body 106 abuts transverse latching projections 128 against bridge 131. The resilient expanding lances 150 allow the inner body 106 to be inserted into the plug 102 as they engage the shoulder 152 of the outer casing 104, while the spring 14 presses against the sleeves 12, 116, creating an opposing biasing force on the inner body 106. Note here. that the bushing 116 extends outwardly beyond the skirt 118 further than the analogous bushing 12 beyond its skirt 35 for reasons that will be explained later.

Figure 6 shows a socket housing 204 which is similar in nature to the socket housing 4 described above. As mentioned above, on the side of the mounting plate, a socket half 80 may be provided with an inner detent member 84 which is identical to that described above. However, on the slave plate side, a special plug housing portion 280 is needed having centrally located rib-type expansion decoupling elements 248 located close to the mating surface of the housing 280. The width of these expansion decoupling elements 248 is profiled to fit between the two cam members 120 (Fig. 8). A different hook member 284 is also needed, which has resilient hook arms 291 significantly longer than the corresponding hook arms 91 of the receptacle 4 discussed previously for reasons that will be described in more detail hereinafter.

The engagement sequence is best illustrated in Figures 9-13. In Figure 9, plug 102 is shown partially inserted into cavity 213 of receptacle 204. Sleeve 116 is partially inserted into centering sleeve 85, and receptacle latch arms 291 are spring loaded outwardly by sliding. wings 294 across the bevelled front cam surfaces 124 of the plug housing 104. The tabs 292 of the arms 291 slide over the web 131 between the cam members 120. In Figure 10, the tabs 292 in the cavity 126 of the insert 109 of the inner body 106 of the plug 102 are located behind the tab 128 to prevent it from being pulled rearward. The tabs 292 extend through the opening 127 between the cam members 120 (see also Fig. 8) and the wings 294 rest on the lower surface 121. In the position shown in Fig. 10 the plug shell 118 of the plug 109 resides on the center portion 288, and the bushings 12 and 116 bear against each other under the action of the spring. In the position of Figure 10, the optical connection between the two pins 2 and 102 is achieved and the pins are releasably engaged with the socket 204. It should be noted that in this situation the shield 118, unlike the shield 35, is spaced apart from the surface. final 289.

However, this is a disadvantage as it allows only a very small tolerance of the axial distance D between the edge of the additional plate 101 and the mounting plate 100. If a gap of less than D was required between the auxiliary plate 101 and the mounting plate 100, a force would have to be applied to the plug housing 104 which would push the resilient expanding lances 150 forward and thereby compress the spring 112 so that the detent 128 of the plug 102 would move. forward away from the detent teeth 292 of the socket 204.

If the spacers 150, 152 are coupled and the distance separating the slave plate 101 from the mounting plate 100 is less than D, the force loop will be as follows: sleeve 116 - piston 114 - spring 112 - insert 109 - expanding lances 150 - outer casing 104 - slave plate 101 - ground - mounting plate 100 - socket 204 catch lugs 92 - plug internal body 6 - coil spring 14 - piston 24 - sleeve 12.

As can be seen from the above, the spring forces are perceived by the plates 100, 101 which are disadvantaged as these forces can be quite large depending on the number of optical connections in the connector. This can cause the plates 100, 101 to deform. Accordingly, a stronger and therefore more costly structure is needed.

To avoid the above-mentioned undesirable situation, the socket housing 204 is provided with expansion decoupling elements 248 which slide between the cam members 120 of the plug 102 as shown in Figs. 9, 10 and 11. In this case, inner surface 249 (Fig. 6) 248 in the form of ribs it is very close to the outer surface 151 of the inner body 106 of the plug. Fig. 11 shows the slave 101 and the plug 102

173 558 inserted deeper into socket 204 so that the rib-like expansion decoupling members 248 are inserted past the shoulder 152 of the outer housing 104 of the plug 102, and the expanding lances 150 are biased inwardly and decoupled from the shoulder 152. Figure 11 is a temporary view because in this position the male body 106 is no longer pushed forward by the resilient expanding lances 150 and would spring backward until the detent teeth 292 abut the detent lugs 128 as shown in Fig. 12.

The coupling force loop shown in Figures 12 and 13 is closed in the joint and is as follows: sleeve 116 - piston 114 - spring 112 - insert 109 - resilient catch arms 291 - inner body 6 - coil spring 14 - socket piston 24 - sleeve 12.

The above-mentioned loop of force does not load the plates, which was the case, as mentioned above, when the expander lances 150 were coupled to the shoulder 152. The outer plug housing 104 and thus also the slave plate 101 can now be moved forward practically without any resistance into position. of Fig. 13 and back to the position of Fig. 12, within a tolerance T of the axial distance of the slave plate 101 from the mounting plate 100, as shown in Fig. 13. This has become possible because the outer plug housing 104, as shown in Figures 12 and 13, is completely freed from the inner plug body 106, the body being held against the mounting plate 100 solely by catch teeth 292 on the tabs 128.

To release the plug from the socket, simply pull back the plug housing 104 as shown in Fig. 14, i.e., retract the slave plate 101. The wings 294 then engage the release cam surface 122 forcing the catch arms 291 to flex outwardly. as shown in Fig. 15, until wings 294 pass over the upper flat cam surface 125 (Fig. 16). This will allow the detent tooth 292 to pass over the detent 128. The plug 102 may then be fully pulled out of the socket as shown in Figure 17 with the expanding lances 150 re-engaging the shoulder 152 to allow the plug 102 and socket 204 to be reconnected.

Figure 18 shows an alternate embodiment of a plug connector 102 'in which expanding lances 150' are integrally formed with the insert 109 and have cam surfaces 149 'cooperating with the rib-like expansion decoupling member 248 on the receptacle housing to detach the insert 109 from the outer. plug housing 104. Fig. 18 further shows an alternative drawbar arm 91 'which is oppositely shaped and has integral wings 94'.

Although the invention has been described with reference to one plug housing 104 shown in Fig. 7, it also applies to Fig. 19. It shows another connector assembly 300 including an electrical connector housing 301 and a fiber optic plug part 302 which has an outer housing 304. Any number of chambers 311 may be provided that will receive the insert members 106 (FIG. 7) identically. Cam members 320 are provided at each chamber 311 for hooking engagement with the insert 106 as previously described. As shown in Fig. 19, housing 304 has a lower surface 330 for abutment on the slave board and a plurality of locating posts 332 that serve to properly align housing 304 on the slave board. As also shown in Fig. 19, the connector portion 301 includes a plurality of terminal inserts 340 which are similar to the solution described in the aforementioned European Patent Application No. EO-A-0 420 785.

A preferred embodiment of the invention has been described above. However, many different shapes, sizes and mounting points of the plug housing, plug tabs, jack housing, socket insert, expansion members, and the shape and number of cam members as well as the number of optical fibers mounted in the connector are conceivable without departing from the spirit of the invention.