HK1064743B - Tunable fiber optic connector - Google Patents

Description

Adjustable optical fiber connector

This application is a PCT international patent application filed in the name of ADC telecommunication shares, designating all countries except the united states.

Technical Field

The invention relates to a tunable optical fiber connector for an optical cable signal transmission system, and relates to an assembling method of the optical fiber connector.

Background of the invention

Optical fiber cables are used in the telecommunications industry to transmit optical signal data at high speeds and in communication systems. A standard optical cable includes an optical fiber having a core for transmitting light. Surrounding the optical fibers are typically a reinforcing layer and an outer jacket.

The optical fiber terminates in a fiber optic connector. Connectors are often used to non-fixedly connect and disconnect optical devices in optical transmission systems. There are many different types of fiber optic connectors. Common connectors are FC and SC connectors. Other types of connectors are also ST and D4 type connectors.

A typical SC fiber optic connector includes a holder having opposite front and rear ends. The front end of the SC connector holder is generally configured to be inserted into an adapter. An example of an adapter is given in us patent No. 5317663, the disclosure of which is hereby incorporated by reference. The SC-type connector also typically includes ferrules disposed within the front and rear ends of the holder, adjacent the front end. The ferrule is axially movable relative to the holder, biasing the spring to urge it in a direction toward the front end of the connector. One end of the cable is stripped. The stripped end includes a length of bare optical fiber extending through the ferrule into the connector.

The connector described above mates with another connector in an adapter, such as the adapter of U.S. Pat. No.5,317,663. The first connector is received at the front of the adapter and the second connector is received at the rear of the adapter. When the two connectors are fully received within the adapter, the two ferrules (and the optical fibers within the ferrules) contact or are in close proximity to each other to ensure signal transmission between the optical fibers.

Signal loss often occurs at the junction of two fiber cores in a system. Because the concentricity of the inner diameter and the outer diameter of the ceramic ferrule has production errors, errors exist between the size of the inner diameter hole of the ceramic ferrule and the outer diameter of the optical fiber, and errors exist in the processing of the concentricity of the optical fiber core and the outer diameter of the optical fiber, when the optical fiber is inserted into the ceramic ferrule, the optical fiber core cannot be perfectly positioned at the circle center of the outer diameter of the ceramic ferrule, and the optical fiber core cannot be perfectly positioned at the circle center of the outer diameter of the ceramic ferrule. If one or both of the fibers are off-center, the fibers will not align when they are connected within the adapter, thereby causing signal loss as the signal propagates through both fibers. There is therefore a need for an adjustable connector that can be used to provide an optimal connection with another connector to minimize signal loss.

Summary of the invention

One aspect of the present invention relates to an optical fiber connector. The connector includes a ferrule retainably engaged within a plug base. The connector also includes a rear holder and a front holder. The rear support is sized to receive and rotatably retain the plug base. The front support base has a through hole that receives and engages the outer surface of the rear support base. The front and rear supports include engagement portions that allow the rear support to be retained in the front support and rotated between discrete positions relative to the front support.

Another aspect of the invention relates to a method of assembling a fiber optic connector. The method includes providing a ferrule retainably engaging a plug base. The assembly is located in a through hole of the rear support base, which rotatably retains the plug base therein. Next, the rear holder is inserted into the through-hole of the front holder, and the rear holder is rotatable within the front holder between discrete positions.

Additional features of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of the invention as claimed.

Brief description of the drawings

The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. The drawings are briefly described as follows:

FIG. 1 is a side view of an unsheathed SC style connector configuration in accordance with the principles of the present invention;

FIG. 2 is a cross-sectional partial side view taken longitudinally along the connector shown in FIG. 1 without the boot between lines 2-2;

fig. 3 is a cross-sectional view of the fully assembled connector of fig. 1, including a jacket disposed at the front of the connector and an optical fiber connected to the connector.

Fig. 4 is a cross-sectional view of the fully assembled connector of fig. 3 rotated 90 degrees about the longitudinal axis to a second orientation.

Fig. 5 is an end view taken along line 5-5 of fig. 4.

Fig. 6 is an end view taken along section line 6-6 of fig. 4.

Fig. 7 is an exploded perspective view of the SC-type connector of the present invention.

Figure 8 is a cross-sectional view of a plug base with a connected ferrule for use in the SC-type connector of the present invention.

Fig. 9 is a cross-sectional view of the front holder of the SC type connector of the present invention.

Fig. 10 is an enlarged partial cross-sectional view of a portion of the collar of the rear holder of the SC-type connector engaged with a socket on the front holder.

Detailed Description

Reference will now be made in detail to exemplary aspects of embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Fig. 1 illustrates an SC-type connector 20 constructed in accordance with the principles of the present invention. The connector 20 includes a holder 22 with a front holder 24 connected to a rear holder 26. A lead-out cover 28 is attached to the rear end 23 of the connector 20. The front portion 49 of the ferrule 48 is shown extending from the front end 25 of the connector 20. Ferrule 48 is mounted to plug base 44 (not shown in fig. 1), both of which are slidably mounted within connector 20. As shown, the rear support base 26 is one piece. It may be constructed in more than one piece, such as described and illustrated in copending application serial No. 09/459,968 filed on 12/13 1999, which is hereby incorporated by reference.

For clarity, the fiber optic cables are not shown in FIG. 1. Also for clarity, an outer jacket slidably located at the front end of the holder, as is common in typical SC-type connectors, is not included in fig. 1. The jacket and cable are shown in other figures and described in combination in the description of the other figures to follow.

Referring to fig. 2, front holder 24 of connector 20 extends along a longitudinal axis 30 and includes a front end 32 opposite a rear end 34. The front support 24 also defines a front chamber 36 and a rear chamber 38. A cross-partition 40 separates the front chamber 36 from the rear chamber 38. The transverse partition 40 defines an aperture 42 centered on the longitudinal axis 30. The front end 32 and the rear end 34 of the front support 24 are open through a through hole 33 (see fig. 4) extending therebetween along the longitudinal axis 30.

The connector 20 also includes a plug base 44 located within the connector 20. The plug base 44 is mounted for longitudinal sliding movement along the longitudinal axis 30 relative to the front support 24. The plug base 44 has apertures 45, 47 at the front 55 and rear 57, respectively, and a through bore 53 extending between the apertures.

The plug base 44 secures the ferrule 48. The ferrule 48 includes a rear portion 51 that fits within the front aperture 45 of the plug base 44. The ferrule 48 may be attached to the plug base 44 by conventional fastening techniques, such as epoxy glue. The plug base 44 may also be assembled to the ferrule 48 with an interference fit or molded around the ferrule. The ferrule 48 includes a through hole 59 for receiving a bare optical fiber. The ferrule 48 extends along the longitudinal axis 30 from the plug base 44 toward the front face 32 of the holder 24. The ferrule 48 extends through the central bore 42 of the bulkhead 40 between the front 36 and rear 38 chambers of the front holder 24 and protrudes from the front end 23 of the connector 20.

The connector 20 also includes a coil spring 56 mounted within the rear chamber 38. Coil spring 56 surrounds a rear portion 57 of plug base 44 and is compressed between a forward shoulder 58 formed by rear support block 26 and a rearward shoulder 60 formed by plug base 44. The spring 56 acts to bias the plug base 44 toward the front end 32 of the front support 24. Because the ferrule 48 is attached to the plug base 44, the spring 56 also functions to bias the ferrule forward.

The rear support base 26 also extends along the longitudinal axis 30 and includes a forward end 62 opposite a rearward end 64. Plug base 44 and surrounding spring 56 slide into bore 27 at front end 62 of rear support block 26. However, plug base 44 and spring 56 are not mechanically fastened to rear support 26 and are therefore free to move longitudinally along shaft 30 relative to rear support 26. The only limitation of the rearward movement of plug base 44 and spring 56 to the position of rear support 26 is the forward facing shoulder 58 on rear support 26, which engages spring 56 as described above. The engagement of the spring 56 with the shoulder 58 acts to bias the plug base 44 and attached ferrule 48 outwardly from the bore 27 at the front end 62 of the rear holder 26.

The front 55 of the plug base 44 and the aperture 27 in the front end 62 of the rear support 26 are sized so that the plug base 44 cannot rotate in the rear support 26 when it is placed in the rear support 26. Likewise, when the plug base is fully inserted into the rear holder 26, the ferrule 48 attached to the plug base 44 cannot rotate relative to the rear holder 26. This is achieved by the non-annular plug base 44 and the corresponding non-annular opening 27 in the front end 62 of the rear support 26. In the illustrated embodiment, the plug base 44 and the aperture 27 in the rear support 26 have the same non-circular shape, such that the plug base 44 can only be received in one orientation in the aperture 27. As shown in fig. 7, the outer periphery of the plug base 44 and the through-hole of the rear holder 26 are each defined by three planar sides 100, an arcuate side 103. Such a configuration may allow plug base 44 to enter rear holder 26 in a unique orientation, and once received in the through-bore, plug base 44 (and ferrule 48) is non-rotatable with respect to rear holder 26. It may be noted that other configurations are possible that allow plug base 44 to be inserted into rear support 26 in a variety of orientations, but that once plug base 44 is received in rear support 26, plug base 44 cannot rotate within rear support 26.

The front support 24 can be seen in more detail in fig. 7 and 9. The rear portion 34 of the front support 24 includes two extensions 66, 68 at the aperture 29 of the rear portion 34. The extensions 66, 68 also define two tapered cutouts 70 extending longitudinally on either side of the front support 24 toward the front end 32 of the front support 24 (fig. 7 shows one tapered cutout 70 of the front support 24 toward the top surface). The cut-out 70 provides resiliency to the extensions 66, 68 so that they deflect outwardly upon application of appropriate pressure from within the aperture 29. Inside each elastic extension 66, 68, closest to the aperture 29 at the rear end 34, there is a pair of protrusions or teeth 74 and 76, which extend into the through hole 33 of the front support 24 (see fig. 5). Between each pair of teeth 74, 76 is a pocket 78. Adjacent the pairs of teeth 74, 76 are slots 80 formed in the resilient extensions 66, 68.

As described above, the front holder 24 is connected to the rear holder 26. The front end 62 of the rear support base 26 is received in the aperture 29 of the rear end 34 of the front support base 24. A collar 82 extends around the outer surface of the rear support base 26. When rear support 26 is inserted into aperture 29 of front support 24, collar 82 compresses against pairs of teeth 74, 76 that protrude into through-hole 33 of front support 24, preventing rear support 26 from being inserted further into front support 24. However, when longitudinal pressure is added to forward seat 24 by rear seat 26, resilient extensions 66, 68 deflect outward, and aperture 29 slightly enlarges to allow collar 82 to clear opposing teeth 74, 76. After passing over the two pairs of teeth 74, 76, the collar 82 snaps into the adjacent socket 80 formed in the front support 24. When this occurs, the resilient extensions 66, 68 snap back to their original positions, engaging the rear support base 26 to the front support base 24. Fig. 10 shows a cross-sectional view of the collar 82 retained in one of the sockets 80. Forward or rearward facing abutment shoulders 86 and 88 define the slot 80 to prevent longitudinal movement of the assembled rear support 26 relative to the front support 24 when the collar 82 is in the slot 80.

The front and rear support brackets 24, 26 also include structure that prevents the rear support bracket from rotating when it is snapped into the front support bracket 24. Adjacent the collar 82 on the rear support base 26 is a ring of projections or teeth 90 that project outwardly around the rear support base 26. The exemplary embodiment shown includes 12 teeth 90 evenly distributed around the circumference of the rear support base 26. These projections 90 can be seen clearly in figures 5 and 7. As described above, when the collar 82 snaps into the socket 80 on the front support 24, the ring of teeth 90 on the outer surface of the rear support 26 acts simultaneously and mates with the pair of protruding teeth 74, 76 in the through hole 33 of the front support 24. The teeth 90 on each rear support 26 are sized to snap into the pockets 78 formed by the pairs of teeth 74, 76. Thus, when rear holder 26 is engaged by front holder 24, two diametrically opposed teeth 90 are pressed into pockets 78 formed by opposed resilient extensions 66 and 68 of front holder 24. The engagement is shown in fig. 5. With this arrangement, the rear support 26 is not free to rotate within the front support 24, but is clamped in discrete positions. However, if the rear support block 26 is twisted relative to the front support block under sufficient rotational pressure, the resilient extensions 66 and 68 will deflect slightly outwardly, allowing the rear support block 26 to rotate within the front support block 24 until a second position is formed on the rear support block 26 where a set of opposing new teeth 90 engage the pockets 78. Because there are 12 different teeth 90 on the rear support 26 in the exemplary embodiment, there are 12 different discrete rotational positions for the rear support 26 to select when rotating within the front support 24. It is understood that the number and configuration of the projections on the front and rear holders 24, 26 may be changed without departing from the scope of the present invention. Other configurations that provide for the selection of discrete rotational positions of rear support 26 within front support 24 consistent with the teachings of the present invention may also be used.

The connector 20 further includes a collet 92. The connector holder 22 is inserted into a through hole 93 formed in the jacket 92. The front holder 24 comprises a structure for mounting the holder 22 in the jacket 92. When the holder 22 is placed in the collet 92, the collet restrains the resilient extensions 66 and 68, preventing them from deflecting outward. Thus, when the collet 92 is attached to the holder 22, the rotational alignment between the front and rear holders 24, 26 cannot be changed by interlocking teeth on the interior of the housing. The outer surface of the holder 22 and the through hole 93 of the collet 92 are configured such that the holder 22 can be fully inserted into the collet in only one orientation. Alternatively, the holder 22 includes other types of external keys. The outer surface of the collet 92 includes a key 94 (see fig. 4 and 7) sized to be received in a slot of an adapter (not shown), such as the adapter of U.S. patent No.5,317,663, where such adapter is to be used with a second SC-type connector. With these arrangements, the connector 20 can be rotated and the front 24 and rear 26 holders rotated relative to each other to align the keys on the holders 22 before locking the rotational orientation of the holders 22, as described in the assembly method below.

The invention is further directed to a method of assembling an SC-type connector. The ferrule 48 is first loaded into the aperture 45 in the front 55 of the plug base 44. Fig. 8 is a cross-sectional side view of such an assembly. The spring 56 is then placed on the rear portion 57 of the plug base 44 and is inserted together into the front end 62 of the rear support block 26. As described above, the front portion 55 of the plug base 44 is sized such that the plug base 44 (and attached ferrule) cannot rotate relative to the rear holder 26 when it is inserted into the rear holder 26.

Next, the rear holder 26 snaps into the front holder 24, thereby retaining the plug base 44 and ferrule (and spring 56) within the holder 22. This connection prevents longitudinal movement of the rear support base 26 relative to the front support base 24. However, this engagement does not prevent rotation between the holders 24, 26.

At this point, a fiber optic cable 96 having optical fibers 98 therein is spliced to connector 20 using conventional techniques known in the art, including stripping the end of cable 96 to expose optical fibers 98. The fiber 98 is then fed into the connector 20 through the through hole 59 of the ferrule 48. The optical fibers may be mechanically or adhesively secured within the ferrule 48. The reinforcing layer of the optical fiber 96 is crimped with the winding sleeve 71. The pull-out cover 28 is attached to the spool cover 71 to assist in strain relief. The bare fiber at the front end 49 of the ferrule 48 can then be polished.

The connector 20 is then adjusted, including measuring eccentricity using suitable testing equipment, to determine if the core inside the fiber 98 is misaligned or if the fiber 98 is misaligned with respect to the ferrule 48. After the direction of such deviation is determined, the rear support 26 is rotated to some optional discrete position within the front support 24. These positions are determined by the rotational position of the projections 90 on the outer surface of the rear support 26 that engage corresponding alignment features of the rear support 26, such as the pockets formed between pairs of projections (e.g., teeth 74, 76) on the inner surface of the front support 24. The selected position is the position where signal loss is minimal when two connectors are connected within the adapter. As mentioned above, the front holder 24 has a shape that ensures that it is inserted into the jacket 92 in a unique orientation. As shown in FIG. 6, the collet 92 includes tabs 95 and 97 that prevent the holder 22 from being installed into the collet 92 when the holder 22 is improperly oriented. Thus, discrete positions are selected to align the direction of insertion of the connector 20 into the jacket 92. Thus, the configuration of the holder becomes a key to the optional discrete positional alignment. Other key elements may also be included on the holder to align the optional discrete positions.

Finally, once the proper rotational position is selected, the connector 20 is inserted into the collet 92. Collet 92 prevents outward deflection of extensions 66 and 68 so that rear holder 26 is rotationally locked to front holder 24 at the selected discrete positions in the front. The connector 20 may then be inserted into an adapter (not shown) to mate with a second SC-type connector.

With respect to the foregoing description, it will be appreciated that changes may be made in details, especially in matters of materials selected, shape, size, arrangement of parts, and the like, without departing from the scope of the invention. It is intended that the specification and description be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims (6)

1. An optical fiber connector comprising:

the ceramic ferrule is provided with a front end and a rear end corresponding to the front end;

a plug base retainably engaging the ferrule;

a support having a rear support and a front support, wherein the plug base is rotatably retained by the rear support, the front support is rotatable relative to the rear support between selectable discrete positions, the rear support has an outer surface with a plurality of teeth extending from the outer surface around the periphery of the rear support, the front support has two pockets located on opposite sides of the longitudinal axis of the front support, each pocket is defined by a first tooth and a second tooth extending from the inner surface of the front support, wherein the rear support is rotatable within the front support, wherein rotation of the rear support within the front support sequentially engages each of the plurality of teeth within at least one pocket, the engagement of each of the plurality of teeth within at least one pocket defines a selectable discrete position, wherein the front support includes a ferrule that flexes outwardly relative to the ceramic when the rear support is inserted into the front support A resilient extension, and wherein when the rear holder is fully positioned in the front holder, the resilient extension returns to its natural position thereby securing the rear holder to the front holder, and wherein the holder has a front end and a rear end, the front end of the ferrule being disposed adjacent the front end of the holder, the plug base being longitudinally movable relative to the holder;

a spring biasing the plug base toward the front end of the holder;

a collet engageable with the support, wherein prior to placement of the collet, the front support is configured to rotate relative to the rear support with sufficient rotational pressure to cause the resilient extension to flex slightly outward to cause the front support to rotate to another selectable discrete position within the rear support, and wherein when the support is placed within the collet, the collet locks the front support to the rear support at one of the selectable discrete positions such that the front support cannot rotate relative to the rear support by resisting outward flexing of the resilient extension, thereby maintaining rotational alignment between the rear and front supports.

2. The connector of claim 1, wherein the rear holder includes at least 12 teeth.

3. The connector of claim 1, wherein the plug base is rotatably retained by a rear holder, the plug base not being longitudinally retained by the rear holder.

4. The connector of claim 1, wherein the connector is an SC-type connector.

5. The connector of claim 1, wherein said rear support defines a non-circularly configured through-hole for receiving said plug base, said plug base having a correspondingly non-circularly configured outer surface.

6. The connector of claim 5, wherein the plug base is inserted into the rear holder in a unique orientation.