Optical fiber ferrule assemblies

• US 5,390,270 A
• Filed: 08/16/1993
• Issued: 02/14/1995
• Est. Priority Date: 11/28/1989
• Status: Expired due to Fees

• Current Assignee: KEL Corporation (Koninklijke Philips N.V.)
• Original Assignee: KEL Corporation (Koninklijke Philips N.V.)
• Inventors: Hanzawa, Hideyuki, Nonaka, Toshihiro
• Primary Examiner(s): Healy, Brian
• Application Number:
  US08/139,046
• Time in Patent Office: 547 Days
• Field of Search: 385/60, 385/62, 385/65, 385/66, 385/70, 385/72, 385/76, 385/78, 385/81, 385/83, 385/84, 385/87, 385/88, 385/89, 385/139, 385/136, 385/137
• US Class Current: 385/81
• CPC Class Codes: G02B 6/3855 characterised by the method of anchoring or fixing the fibre within the ferrule G02B6/3854 takes precedence
• CPC Class Codes: G02B 6/3862 radially-compressed, longitudinally-split ferrules consisting of a pair of identical matching halves
• CPC Class Codes: G02B 6/3865 fabricated by using moulding techniques shaping techniques of plastic materials in general B29C; producing plastic optical fiber connectors B29D11/0075
• CPC Class Codes: G02B 6/3878 comprising a plurality of ferrules, branching and break-out means

Abstract

An inner, optical fiber core clamping ferrule has an optical fiber clamping portion for receipt in an outer ferrule and defining an axially extending through-passageway, an axial slit extending through the clamping portion divides the passageway into two opposed groove portions receiving a prepared end of an optical fiber extending along the through-passageway. The inner ferrule is force-fitted in the outer ferrule to extend co-axially therewith, with wall portions thereof maintaining the opposed walls of the spaced apart slit in open condition so that opposed walls of the groove portions are pressed into gripping engagement with the optical fiber. The opposed walls of the slit diverge as they extend radially outwardly away from the groove portions. The inner ferrule may be split for the entire length of the through passageway forming two halve hinged together at one end or have open slits formed in an otherwise imperforate tubular wall.

Claims

1. A ferrule assembly for terminating an optical fiber comprising:

an outer ferrule comprising a tubular body wall having front, mating and rear, optical fiber receiving axial ends;

an inner optical fiber clamping ferrule comprising a tubular body having a front, axial end and a rearwardly extending optical fiber clamping portion for receipt in the outer ferrule and defining an axially extending through-passageway, an axial slit extending through the clamping portion dividing the passageway into two opposed groove portions so that a prepared end of an optical fiber can be located in the groove portions extending along the through-passageway and the inner ferrule subsequently force-fitted within the outer ferrule to extend co-axially therewith, wall portions of the inner ferrule body at opposite axial ends of the slit maintaining axially extending portions of both respective opposed surfaces of the slit spaced apart from each other with the slit in open condition so that opposed walls of the groove portions are pressed into gripping engagement with the optical fiber therein by the receipt of the inner ferrule in the outer ferrule retaining the optical fiber centered accurately in the ferrule assembly.

2. A ferrule assembly according to claim 1 in which the spaced apart, opposed slit surfaces diverge as they extend radially outwardly away from the groove portions.

3. A ferrule assembly according to claim 2 in which the inner ferrule is cylindrical and said clamping portions are fan-shaped in transverse cross-section in the region of the open slit.

4. A ferrule assembly according to claim 1 in which the slit extends through diametrically opposite locations of the clamping portion.

10. A ferrule assembly according to claim 1 in which the outer ferrule comprises an outer sleeve formed as a single piece of plastic material and a rigid, reinforcing tube received in the outer sleeve in co-axial relation therewith as a force fit forming a sub-assembly, the inner ferrule forming the force fit with the reinforcing tube.

11. A ferrule assembly according to claim 2 in which the outer ferrule comprises an outer sleeve formed as a single piece of plastic material and a rigid, reinforcing tube received in the outer sleeve in co-axial relation therewith as a force fit forming a sub-assembly, the inner ferrule forming the force fit with the reinforcing tube.

12. A ferrule assembly according to claim 1 in which the outer ferrule comprises an outer sleeve formed as a single piece of plastic material and a rigid, reinforcing tube received in the outer sleeve in co-axial relation therewith as a force fit forming a sub-assembly, the inner ferrule forming the force fit with the reinforcing tube.

21. A ferrule assembly according to claim 1 in which at least one axially extending, fiber retaining section of a groove portion is non-aligned axially both with a remainder of the groove portion of the clamping part in which it is formed and with a fiber retaining section of the other groove part so that the respective axes of the fiber retaining sections are laterally displaced and so that, when opposed walls of the groove portions are pressed into gripping engagement with the optical fiber with the fiber retaining sections in opposed overlying relation, longitudinal edges of the fiber retaining sections of respective groove portions will press opposite sides of optical cladding of the fiber in opposite lateral directions thereby restraining axial movement of the fiber relative to the inner ferrule.

22. A ferrule assembly according to claim 21 in which the respective axes of the fiber retaining sections are laterally displaced in respective opposite directions from each other to respective opposite sides of the axes of the remainders of groove portions with which they are contiguous.

23. A ferrule assembly according to claim 22 in which there are a plurality of contiguous fiber retaining sections in each clamping portion which are laterally displaced in respective opposite directions from each other to respective opposite sides of the axes of the remainders of groove portions with which they are contiguous.

5. A ferrule assembly for terminating an optical fiber comprising:

an outer ferrule comprising a tubular body wall having front, mating and rear, optical fiber receiving axial ends;

an inner optical fiber clamping ferrule made of plastic material and comprising a tubular body having a front, axial end and a rearward extending optical fiber clamping portion for receipt in the outer ferrule and defining an axially extending through-passageway, an axial slit extending through the clamping portion dividing the body into a pair of optical fiber clamping halves integrally joined together by web hinges extending from the front ends on respective opposite sides of the through-passageway, and dividing the passageway into two opposed groove portions, each clamping half being formed with one of the groove portions so that a prepared end of an optical fiber can be located in the groove portions extending along the through-passageway and the inner ferrule subsequently force-fitted within the outer ferrule to extend co-axially therewith, wall portions of the inner ferrule body at opposite axial ends of the slit maintaining axially extending portions of opposed surfaces of the slit spaced apart from each other with the slit in open condition so that opposed walls of the groove portions are pressed into gripping engagement with the optical fiber therein by the receipt of the inner ferrule in the outer ferrule retaining the optical fiber centered accurately in the ferrule assembly.

6. A ferrule assembly according to claim 5 in which respective clamping halves are provided with mating lugs and sockets, interengagable on positioning the clamping halves together with the respective slit surfaces in face-to-face relation, thereby maintaining the respective groove portions accurately aligned with each other.

24. A ferrule assembly according to claim 5 in which at least one axially extending, fiber retaining section of a groove portion of a clamping half is non-aligned axially both with a remainder of the groove portion of the clamping half in which it is formed and with a fiber retaining section of the groove portion of the other clamping half so that the respective axes of the fiber retaining sections are laterally displaced and so that, when opposed walls of the groove portions are pressed into gripping engagement with the optical fiber with the fiber retaining sections in opposed overlying relation, longitudinal edges of the fiber retaining sections of respective clamping portions will press opposite sides of optical cladding of the fiber in opposite lateral directions thereby restraining axial movement of the fiber relative to the inner ferrule.

25. A ferrule assembly according to claim 24 in which the respective axes of the fiber retaining sections are laterally displaced in respective opposite directions from each other to respective opposite sides of the axes of the remainders of groove portions with which they are contiguous.

26. A ferrule assembly according to claim 25 in which there are a plurality of contiguous fiber retaining sections in each clamping portion laterally displaced in respective opposite directions from each other to respective opposite sides of the axes of the remainders of groove portions with which they are contiguous.

7. A ferrule assembly for terminating an optical fiber comprising:

an outer ferrule comprising a tubular body wall having front, mating and rear, optical fiber receiving axial ends;

an inner optical fiber clamping ferrule comprising a tubular body having a front, axial end and a rearward extending optical fiber clamping portion for receipt in the outer ferrule, and defining an axially extending through-passageway, the clamping portion being formed with two axially spaced clamping sections for clamping a bare optical fiber and sheath, respectively, and being of increased diameters providing radially outwardly protruding interference portions forming interference fits within the outer ferrule, two axially extending slits located in longitudinal spaced apart relation extending through opposite sides of the clamping portion in respective clamping sections dividing the passageway into two opposed groove portions so that a prepared end of an optical fiber can be located in the groove portions extending along the through-passageway and the inner ferrule subsequently force-fitted within the outer ferrule to extend co-axially therewith, wall portions of the inner ferrule body at respective opposite axial ends of each slit maintaining axially extending portions of opposed surfaces of each slit spaced apart from each other with the slit in open condition so that opposed walls of the groove portions of the respective clamping sections are pressed into gripping engagement with the bare optical fiber and sheath therein, respectively, by the receipt of the inner ferrule in the outer ferrule, retaining the optical fiber centered accurately in the ferrule assembly.

8. A ferrule assembly according to claim 7 in which the wall portions are imperforate.

9. A ferrule assembly according to claim 7 in which the spaced apart, opposed slit surfaces diverge as they extend radially outwardly away from the groove portions.

13. A ferrule assembly according to claim 7 in which the outer ferrule comprises an outer sleeve formed as a single piece of plastic material and a rigid, reinforcing tube received in the outer sleeve in co-axial relation therewith as a force fit forming a sub-assembly, the inner ferrule forming the force fit with the reinforcing tube.

14. A ferrule assembly according to claim 9 in which in which the outer ferrule comprises an outer sleeve formed as a single piece of plastic material and a rigid, reinforcing tube received in the outer sleeve in co-axial relation therewith as a force fit forming a sub-assembly, the inner ferrule forming the force fit with the reinforcing tube.

15. A ferrule assembly according to claim 7 in which the radially protruding interference portions are axially joined at respective opposite axial ends by body wall portions of reduced diameter radially spaced apart from the outer ferrule.

16. A ferrule assembly according to claim 13 in which the radially protruding interference portions are axially joined on respective opposite axial ends by body wall portions of reduced diameter radially spaced apart from the reinforcing tube of the outer ferrule.

17. A ferrule assembly according to claim 16 in which the clamping sections are joined together axially by an imperforate body wall portion.

27. A ferrule assembly according to claim 7 in which at least one axially extending, fiber retaining section of a groove portion of a clamping section is non-aligned axially both with a remainder of the groove portion of the clamping section in which it is formed and with a fiber retaining section of the opposed groove portion so that the respective axes of the fiber retaining sections are laterally displaced and so that, when opposed walls of the groove portions of the clamping section are pressed into gripping engagement with the optical fiber, longitudinal edges of the fiber retaining sections of respective clamping portions will press opposite sides of optical cladding of the fiber in opposite lateral directions thereby restraining axial movement of the fiber relative to the inner ferrule.

28. A ferrule assembly according to claim 27 in which the respective axes of the fiber retaining sections are laterally displaced in respective opposite directions from each other to respective opposite sides of the axes of the remainders of groove portions with which they are contiguous.

29. A ferrule assembly according to claim 28 in which there are a plurality of contiguous fiber retaining sections in each clamping portion which are laterally displaced in respective opposite directions from each other to respective opposite sides of the axes of the remainders of groove portions with which they are contiguous.

18. A ferrule assembly for terminating an optical fiber comprising:

an outer ferrule comprising a tubular body wall having front, mating and rear, optical fiber receiving axial ends;

an inner optical fiber clamping ferrule comprising a tubular body having a front, axial end and a rearward extending optical fiber clamping portion for receipt in the outer ferrule and defining an axially extending through-passageway, an axial slit extending through the clamping portion dividing the body into a pair of optical fiber clamping parts and dividing the passageway into two opposed groove portions, each clamping part being formed with one of the groove portions so that a prepared end of an optical fiber can be located in the groove portions extending along the through-passageway and the inner ferrule subsequently force-fitted within the outer ferrule to extend co-axially therewith, and so that opposed walls of the groove portions are pressed into gripping engagement with the optical fiber therein by the receipt of the inner ferrule in the outer ferrule retaining the optical fiber centered accurately in the ferrule assembly, at least one axially extending, fiber retaining section of a groove portion of a clamping part being non-aligned axially both with a remainder of the groove portion of the clamping part in which it is formed and with a fiber retaining section of the groove portion of the other clamping part so that the respective axes of the fiber retaining sections are laterally displaced, and so that, when opposed walls of the groove portions are pressed into gripping engagement with the optical fiber with the fiber retaining sections in opposed overlying relation, longitudinal edges of the fiber retaining sections of respective clamping parts will press opposite sides of optical cladding of the fiber in opposite lateral directions thereby restraining axial movement of the fiber relative to the inner ferrule.

19. A ferrule assembly according to claim 18 in which the respective axes of the fiber retaining sections are laterally displaced in respective opposite directions from each other to respective opposite sides of the axes of the remainders of groove portions with which they are contiguous.

20. A ferrule assembly according to claim 19 in which there are a plurality of contiguous fiber retaining sections in each clamping part laterally displaced in respective opposite directions from each other to respective opposite sides of the axes of the remainders of groove portions with which they are contiguous.