# Patent

## Title
Field terminatable fiber optic connector assembly

## Abstract

A fiber optic connector assembly includes a connector and a carrier. The connector, defining a longitudinal bore extending through the connector and having a first end region and a second end region, includes a ferrule assembly, having an optical fiber extending through the connector, at least partially disposed in the longitudinal bore at the first end region, a tube, defining a passage and having a first end portion disposed in the longitudinal bore at the second end region and a second end region, and a spring disposed in the bore between the ferrule assembly and the tube. The carrier includes a cable end and a connector end engaged with the connector, a termination region disposed between the connector end and the cable end, a fiber support region disposed between the connector end and the termination region, and a take-up region disposed between the connector end and the fiber support region.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application is a divisional of U.S. patent application Ser. No. 11/735,267 (now pending), entitled “Field Terminatable Fiber Optic Connector Assembly” and filed on Apr. 13, 2007, which is hereby incorporated by reference in its entirety.


TECHNICAL FIELD
The present invention relates to a fiber optic connector assembly, and more particularly, to a field terminatable fiber optic connector assembly.
BACKGROUND
The use of fiber optic networks as a signal-carrying medium for communications is now extremely widespread and continues to increase. Fiber optic networks frequently include a plurality of fiber optic cables having optical fibers. As fiber optic networks continue to grow, the need for optical fiber terminations for maintenance or expansion purposes is also growing. As such, there is a need for an optical fiber termination which can be used in the field in order to terminate an optical fiber or optical fibers.
SUMMARY
An aspect of the present disclosure relates to a fiber optic connector assembly comprising a connector and a carrier. The connector defines a longitudinal bore extending through the connector and has a first end region and an oppositely disposed second end region. The connector includes a ferrule assembly, which includes an optical fiber that extends through the connector, at least partially disposed in the longitudinal bore at the first end region, a tube, which has a first end portion disposed in the longitudinal bore at the second end region and an oppositely disposed second end region, and a spring disposed in the bore between the ferrule assembly and the tube. The tube defines a passage. The carrier includes a connector end engaged with the connector and an oppositely disposed cable end, a termination region disposed between the connector end and the cable end, a fiber support region disposed between the connector end and the termination region for supporting the optical fiber, and a take-up region disposed between the connector end and the fiber support region.
A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of features. It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.



BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and together with the description serve to further explain the principles of the invention. Other aspects of the present invention and many of the attendant advantages of the present invention will be readily appreciated as the present invention becomes better understood by reference to the following Detailed Description when considered in connection with the accompanying drawings, and wherein:
FIG. 1 is a perspective view of a fiber optic connector assembly made in accordance with the present invention.
FIG. 2 is an exploded view of the fiber optic connector assembly of FIG. 1.
FIG. 3 is a cross-sectional view of the fiber optic connector assembly taken on line 3-3 of FIG. 1.



DETAILED DESCRIPTION
Reference will now be made in detail to the exemplary aspects of the present invention that 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.
Referring now to FIG. 1, a fiber optic connector assembly, generally designated 11, for use in field terminating an optical fiber or optical fibers is shown. The fiber optic connector assembly 11 includes a carrier, generally designated 13, and at least one connector, generally designated 15. While the connector 15 of the subject embodiment of the present invention will be described with regard to an LX.5 connector, which has been described in detail in U.S. Pat. Nos. 5,883,995 and 6,142,676 and hereby incorporated by reference, it will be understood by those skilled in the art that the scope of the present invention is not limited to the use of an LX.5-type connector. While the teachings of the present invention could be used with one or more connectors 15, the subject embodiment of the present invention will be described as having two connectors without intending any limitations on the scope of the present invention.
Referring now to FIG. 2, the carrier 13 will be described. The carrier 13 includes a connector end 17 and a cable end 19, which is oppositely disposed from the connector end 17. In the subject embodiment, the connector end 17 defines slots 23 for mounting the connectors 15. It will be understood by those skilled in the art, however, that the scope of the present invention is not limited to the carrier 13 defining slots 23 for mounting the connectors 15. Disposed between the connector end 17 and the cable end 19 of the carrier 13 is a fiber support region 25. In the subject embodiment, the fiber support region 25 includes guide ways 27 that narrow as the depth of the guide ways 27 in the fiber support region 25 increase. The carrier 13 further defines a take-up region 29, the purpose of which will be described subsequently, that is disposed between the connector end 17 and the fiber support region 25.
A termination region, generally designated 31, is disposed between the cable end 19 of the carrier 13 and the fiber support region 25. The termination region 31 of the carrier 13 defines guide paths 33 that are generally aligned with the guide ways 27 and crimp tube holes 35 defined by the cable end 19. In the subject embodiment, the guide paths 33 narrow as the depth of the guide paths 33 in the termination region 31 increase. The termination region 31 further defines a cavity 37. The cavity 37 is adapted to receive a V-groove chip, generally designated 39.
The V-groove chip 39 in the fiber optic connector assembly 11 serves as the location for the termination of the cleaved optical fibers 41. The V-groove chip 39 includes a base 43 and a cover 45. The base 43 defines V-grooves 47 that support the cleaved optical fibers 41. Cones 49 are disposed on either side of the V-grooves 47 in order to assist in the insertion of the cleaved optical fibers 41 into the V-grooves 47. In the subject embodiment, the base 43 is made of a silicon material while the cover 45 is made of a transparent material such as pyrex. The cover 45 is bonded to the base 43.
The termination region 31 in the carrier 13 includes an adhesive region 51 disposed between the cavity 37 and the cable end 19. Disposed in the adhesive region 51 is a heat responsive adhesive element, generally designated 53, and a saddle assembly, generally designated 55. In the subject embodiment, the heat responsive adhesive element 53 is a glue pellet 53. The glue pellet 53 is shown as being generally rectangular in shape, although it will be understood by those skilled in the art that the scope of the present invention is not limited to the glue pellet 53 being rectangular in shape. The glue pellet 53 includes a first surface 57 and an oppositely disposed second surface 59. At least one pathway 61 is pre-formed in the glue pellet 53. In the subject embodiment, the at least one pathway 61 is a channel 61 that is pre-formed in the second surface 59 of the glue pellet 53. In the preferred embodiment, two channels 61 are pre-formed in the second surface 59. The channels 61 are adapted to receive a portion of the cleaved optical fibers 41 and a portion of buffers 63, which surround the cleaved optical fibers 41. In the subject embodiment, each of the channels 61 is arcuately shaped so as to conform to the outer surface of the buffers 63.
In the subject embodiment, the saddle assembly 55 includes a saddle, generally designated 65, and a resistor 67. The glue pellet 53 is in thermally conductive contact with the saddle 65, which is in thermally conductive contact with the resistor 67. In the subject embodiment, the first surface 57 of the glue pellet 53 is in contact with a bottom surface 69 of the saddle 65, thereby establishing the thermally conductive contact between the glue pellet 53 and the saddle 65. The resistor 67 is in contact with a top surface 71 of the saddle 65, thereby establishing the thermally conductive contact between the resistor 67 and the saddle 65. A portion of the outer surface of each buffer 63 is disposed in channels 61 of the glue pellet 53. In the subject embodiment, nearly half of the outer circumference of the outer surface of the buffers 63 is disposed in the channels 61.
The carrier 13 further includes crimp tubes 73, which are engaged with the cable end 19 of the carrier 13. In the subject embodiment, the crimp tubes 73 are in a press-fit engagement with the crimp tube holes 35 in the cable end 19 of the carrier 13. The crimp tubes 73 define passageways 75 through which the cleaved optical fibers 41 are inserted. Strength members/layers (e.g., Kevlar) of a fiber optic cable can be crimped outside the crimp tube 73 for securing the fiber optic cable.
Referring now to FIG. 3, the connector 15 will be described. The connector 15 includes a main body 77 having a front end region 79 and an oppositely disposed back end region 81. The main body 77 defines a longitudinal bore 83 that extends through the front and back end regions 79, 81. A ferrule assembly, generally designated 85, includes a ferrule 87, an optical fiber 89, a portion of which is housed in the ferrule 87, and a hub 91 having a flange 93 connectedly engaged with the ferrule 87. The ferrule assembly 85 is disposed in the longitudinal bore 83 of the connector 15 such that the ferrule 87 is positioned in the front end region 79 of the main body 77.
The connector 15 further includes a tube, generally designated 95. The tube 95 has a first end portion 97 and an oppositely disposed second end portion 99 and defines a passage 101 through the tube 95. The first end portion 97 of the tube 95 is connectedly engaged with the longitudinal bore 83 at the back end portion 81 of the main body 77. In the subject embodiment, the connected engagement between the tube 95 and the main body 77 is a press-fit engagement. In the subject embodiment, an inner diameter D1 of the passage 101 at the first end portion 97 of the tube 95 is smaller than an inner diameter D2 of the passage 101 at the second end portion 99. The purpose for the difference in the inner diameters D1, D2 of the passage 101 between the first and second end portions 97, 99, respectively, will be described subsequently. The tube 95 further includes an annular groove 103 disposed in the outer surface of the tube 95 between the first end portion 97 and the second end portion 99.
Disposed between the ferrule assembly 85 and the tube 95 is a spring 105. A first end 107 of the spring 105 abuts the flange 93 of the hub 91 while an oppositely disposed second end 109 of the spring 105 abuts an end surface 111 of the first end portion 97 of the tube 95. While the spring 105 biases the ferrule assembly 85 toward the front end region 79 of the main body 77, the spring 105 allows for axial movement of the ferrule assembly 85 within the longitudinal bore 83. In the subject embodiment, and by way of example only, the spring 105 allows for at least 1 mm of axial movement of the ferrule assembly 85.
With the ferrule assembly 85, tube 95, and spring 105 disposed in the main body 77, the connector 15 can be connected to the carrier 13. To connect the connector 15 to the carrier 13, the connector 15 is inserted into the slot 23 of the carrier 13 such that the slot 23 is disposed in the annular groove 103 of the tube 95. In the subject embodiment, the annular groove 103 is in a press-fit engagement with the slot 23. With the connector 15 engaged with the carrier 13, dust boots 112 are inserted over fiber ends 113 of the optical fibers 89, which extend through the longitudinal bore 83 of the main body 77 and the passage 101 of the tube 95. The dust boots 112 are in tight-fit engagement with the second end portion 99 of the tube 95. The fiber ends 113 of the optical fibers 89 are then inserted through the cones 49 of the V-groove chip 39 and into the V-grooves 47. With the fiber ends 113 of the optical fibers 89 inserted into the V-grooves 47 of the V-groove chip 39, the optical fibers 89 are secured to the guide ways 27 of the fiber support region 25. In the subject embodiment, the optical fibers 89 are affixed to the guide ways 27 with an epoxy. The affixation of the optical fibers 89 in the guide ways 27 prevents the fiber ends 113 of the optical fibers 89 from moving axially within the V-grooves 47 of the V-groove chip 39.
As stated previously, the spring 105 allows the ferrule assembly 85 to move axially within the longitudinal bore 83 of the main body 77 toward the carrier 13. With the optical fibers 89 affixed to the guide ways 27 of the fiber support region 25, the axial movement of the ferrule assembly 85 causes the optical fibers 89 to bend between the fiber support region 25 and the ferrule 87. However, if this bend has a radius that is smaller than the minimum recommended bend radius of the optical fibers 89, damage to the optical fibers 89 will result.
Two dimensions in the fiber optic connector assembly 11 are important in ensuring that the optical fibers 89 do not have a bend radius below minimum recommendations. The first dimension is the inner diameter of the passage 101. As the inner diameter of the passage 101 decreases, the number of bends in the optical fiber 89 increases. However, as the number of bends increase, the radii of each bend in the optical fiber 89 decreases. Therefore, there is a directly proportional relationship between the inner diameter of the passage 101 and the bend radius in the optical fiber 89. The second dimension is a length L of the take-up region 29. As the length L increases, the radii of the bends of the optical fibers 89 increases. Therefore, there is a directly proportional relationship between the length L and the bend radius of the optical fiber 89.
In the subject embodiment, the inner diameter D2 of the passage 101 must be sized appropriately to account for the axial movement of the ferrule assembly 85 and the length L of the take-up region 29. If the length L of the take-up region 29 is long, the inner diameter D2 of the passage 101 can be smaller since the bend radius of the optical fibers 89 will be large. On the other hand, if the length L of the take-up region 29 is short, the inner diameter D2 of the passage 101 must be larger to avoid the bend radius of the optical fibers 89 being below the minimum recommendations.
As stated previously, the spring 105 abuts the end surface 111 of the first end portion 97 of the tube 95. In order to have a proper surface against which the spring 105 would act, the end surface 111 of the first end portion 97 of the tube 95 must have sufficient surface area to support the spring 105. Therefore, in order to provide a sufficient surface area to support the spring 105, the inner diameter of the passage 101 should be small. As state above, the inner diameter of the passage 101 could be reduced if the length L of the take-up region 29 was sufficiently long. This would result, however, in the fiber optic connector assembly 11 having a longer overall length, which is not desirable in some applications. Therefore, the subject embodiment resolves this dimensional conflict by having the inner diameter D1 at the first end portion 97 of the tube 95 smaller than the inner diameter D2 at the second end portion 99 of the tube 95. In the subject embodiment, and by way of example only, with the ferrule assembly 85 having an axial movement of at least 1 mm in the longitudinal bore 83, the inner diameter D1 is about 950 μm while the inner diameter D2 is about 3 mm (or about three times greater than the inner diameter D1). By having the inner diameter D2 at the second end portion 99 of the tube 95 larger than the inner diameter D1 at the first end portion 97 of the tube 95, the fiber optic connector assembly 11 can be more compact.
Referring now to FIGS. 2 and 3, the use of the fiber optic connector assembly 11 for a field termination will be described. With the connector 15 engaged to the carrier 13, the optical fiber 89 affixed in the guide way 27 of the fiber support region 25, and the fiber ends 113 inserted into the V-groove 47 of the V-groove chip 39, a cleaved end 115 of the cleaved optical fiber 41 is inserted into the passageway 75 of the crimp tube 73. The cleaved end 115 of the cleaved optical fiber 41 is inserted through the channel 61 of the glue pellet 53 and into the V-groove 47 of the V-groove chip 39. In the subject embodiment, an index matching gel is disposed between the cleaved end 115 of the cleaved optical fiber 41 and the fiber end 113 of the optical fiber 89. The index matching gel has an index of refraction that matches the index of refraction of the glass of the optical fiber 89 and the cleaved optical fiber 41.
With the cleaved end 115 of the cleaved optical fiber 41 inserted into the V-groove 47, optical radiation is passed through the optical fibers 89 to assess proper alignment of the fiber end 113 and the cleaved end 115. If optical radiation is detectable at the junction of the fiber end 113 and the cleaved end 115 as viewed through the transparent cover 45 of the V-groove chip 39, then the alignment/abutment is not correct. The cleaved end 115 may have to be polished or cleaned and reinserted into the V-groove 47. If little to no radiation is detectable at the junction of the fiber end 113 and the cleaved end 115, then the cleaved optical fiber 41 and the buffer 63 can be secured to the fiber optic connector assembly 11 by the glue pellet 53. To secure the cleaved optical fiber 41 and the buffer 63 to the fiber optic connector assembly 11, an electrical power source is connected to the resistor 67. Electrical current is passed through the resistor 67 which heats up the glue pellet 53 by way of the thermally conducting saddle 65. As the glue pellet 53 heats up, the glue pellet 53 becomes tacky and adheres to the buffer 63 and the cleaved optical fibers 41 and closes passageways 75 of the crimp tubes 73. When the current is interrupted, the glue pellet 53 resets to secure the buffers 63 and the cleaved optical fibers 41 in their correct position in alignment with the optical fibers 89.
With the cleaved optical fibers 41 secured, the fiber optic connector assembly 11 can be provided as an insert for a housing to protect the fiber optic connector assembly 11 from damage. One housing in which the fiber optic connector assembly 11 can be inserted is described in a U.S. patent application Ser. No. 11/787,197 titled “Hybrid fiber/copper connector system and method”,  filed concurrently herewith, and hereby incorporated by reference.
Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth herein.

## Claims

1. A fiber optic connector assembly comprising:
a connector defining a longitudinal bore extending through the connector and having a first end region and an oppositely disposed second end region, a ferrule assembly at least partially disposed in the longitudinal bore at the first end region having an optical fiber that extends through the connector, a tube having a first end portion disposed in the longitudinal bore at the second end region and an oppositely disposed second end region, a spring disposed in the bore between the ferrule assembly and the tube, wherein the tube defines a passage;
a carrier having a connector end engaged with the connector and an oppositely disposed cable end, a termination region disposed between the connector end and the cable end, a fiber support region disposed between the connector end and the termination region for supporting the optical fiber, and a take-up region disposed between the connector end and the fiber support region; and
a V-groove chip disposed in the termination region of the carrier.

2. A fiber optic connector assembly as claimed in claim 1, wherein the ferrule assembly has at least 1 mm of axial movement inside the longitudinal bore.

3. A fiber optic connector assembly as claimed in claim 2, wherein the inner diameter of the passage of the tube at the first end portion is smaller than the inner diameter of the passage of the tube at the second end portion.

4. A fiber optic connector assembly as claimed in claim 3, wherein the inner diameter of the passage of the tube at the first end portion is about 950 μm.

5. A fiber optic connector assembly as claimed in claim 4, wherein the inner diameter of the passage of the tube at the second end portion is about 3 mm.

6. A fiber optic connector assembly as claimed in claim 1, wherein the tube is engaged with the connector end of the carrier.

7. A fiber optic connector assembly as claimed in claim 6, wherein the tube is in press-fit engagement with the connector end of the carrier.

8. A fiber optic connector assembly as claimed in claim 1, wherein the optical fiber is affixed to the fiber support region.

9. A fiber optic connector assembly as claimed in claim 8, wherein the optical fiber is affixed to the fiber support region by epoxy.

10. A fiber optic connector assembly comprising:
a connector defining a longitudinal bore extending through the connector and having a first end region and an oppositely disposed second end region, a ferrule assembly at least partially disposed in the longitudinal bore at the first end region having an optical fiber that extends through the connector, a tube having a first end portion disposed in the longitudinal bore at the second end region and an oppositely disposed second end region, a spring disposed in the bore between the ferrule assembly and the tube, wherein the tube defines a passage;
a carrier having a connector end engaged with the connector and an oppositely disposed cable end, a termination region disposed between the connector end and the cable end, a fiber support region disposed between the connector end and the termination region for supporting the optical fiber, and a take-up region disposed between the connector end and the fiber support region;
a V-groove chip disposed in the termination region of the carrier; and
a heat responsive adhesive element disposed in the termination region of the carrier.

11. A fiber optic connector assembly as claimed in claim 10, wherein the ferrule assembly has at least 1 mm of axial movement inside the longitudinal bore.

12. A fiber optic connector assembly as claimed in claim 10, wherein the inner diameter of the passage of the tube at the first end region is smaller than the inner diameter of the passage of the tube at the second end region.

13. A fiber optic connector assembly as claimed in claim 10, wherein the tube is engaged with the connector end of the carrier.

14. A fiber optic connector assembly as claimed in claim 13, wherein the tube is in press-fit engagement with the connector end of the carrier.

15. A fiber optic connector assembly as claimed in claim 10, further comprising a dust boot disposed over the optical fiber between the fiber support region and the connector end.