U.S. patent application number 11/449237 was filed with the patent office on 2006-10-26 for fiber optic connector for applying axial biasing force to multifiber ferrule.
Invention is credited to Terry L. Cooke, Michael deJong, Robert B. II Elkins, Tory A. Klavuhn, James P. Luther, Lars K. Nielsen, Thomas Theuerkorn.
Application Number | 20060239619 11/449237 |
Document ID | / |
Family ID | 34377125 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060239619 |
Kind Code |
A1 |
Luther; James P. ; et
al. |
October 26, 2006 |
Fiber optic connector for applying axial biasing force to
multifiber ferrule
Abstract
A fiber optic connector includes a multifiber ferrule and at
least one force centering element for applying a biasing force to
the ferrule in the longitudinal direction without introducing a
moment about a lateral axis. The connector further includes a coil
spring for exerting the biasing force and a spring seat disposed
between the coil spring and the ferrule. The rearward portion or
the forward portion of the spring seat may be provided with a pair
of outwardly extending protrusions that are laterally spaced apart
to transfer the biasing force to the ferrule. Alternatively, the
forward portion of the spring seat or the rear face of the ferrule
may define a convex surface. Alternatively, the ferrule defines a
convex surface in the direction of a first lateral axis and the
spring seat defines a convex surface in the direction of a second
lateral axis perpendicular to the first lateral axis.
Inventors: |
Luther; James P.; (Hickory,
NC) ; Cooke; Terry L.; (Hickory, NC) ; deJong;
Michael; (Ft. Worth, TX) ; Elkins; Robert B. II;
(Hickory, NC) ; Nielsen; Lars K.; (Denver, NC)
; Theuerkorn; Thomas; (Hickory, NC) ; Klavuhn;
Tory A.; (Newton, NC) |
Correspondence
Address: |
CORNING CABLE SYSTEMS LLC
P O BOX 489
HICKORY
NC
28603
US
|
Family ID: |
34377125 |
Appl. No.: |
11/449237 |
Filed: |
June 8, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10675352 |
Sep 30, 2003 |
7077576 |
|
|
11449237 |
Jun 8, 2006 |
|
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Current U.S.
Class: |
385/69 ; 385/55;
385/56; 385/59; 385/60; 385/62 |
Current CPC
Class: |
G02B 6/3885 20130101;
G02B 6/3821 20130101 |
Class at
Publication: |
385/069 ;
385/055; 385/056; 385/059; 385/060; 385/062 |
International
Class: |
G02B 6/38 20060101
G02B006/38 |
Claims
1-4. (canceled)
5. A fiber optic connector comprising: a multifiber ferrule having
an end face and an opposed rear face, the end face defining a
plurality of optical fiber bores opening therethrough for receiving
respective optical fibers, the fiber optic connector defining a
longitudinal axis that is generally parallel to each of the optical
fiber bores; at least one force centering element for applying a
biasing force to the ferrule in the direction of the longitudinal
axis without generating a moment about a lateral axis defined by
the end face of the ferrule; and a spring seat having a forward
portion that engages the rear face of the ferrule and a rearward
portion opposite the forward portion, the forward portion
comprising the at least one force centering element.
6. A fiber optic connector according to claim 5 wherein the at
least one force centering element is disposed medially on the
forward portion and comprises a protrusion that extends outwardly
from the forward portion.
7. A fiber optic connector according to claim 6 wherein the
rearward portion engages a coil spring that exerts the biasing
force on the ferrule and wherein the protrusion engages the rear
face of the ferrule to transfer the biasing force to the
ferrule.
8. A fiber optic connector according to claim 5 wherein the spring
seat comprises an arcuate side wall for engaging an interior
surface of a connector housing such that the spring seat is movable
only in the direction of the longitudinal axis.
9. A fiber optic connector comprising: a multifiber ferrule having
an end face and an opposed rear face, the end face defining a
plurality of optical fiber bores opening therethrough for receiving
respective optical fibers, the fiber optic connector defining a
longitudinal axis that is generally parallel to each of the optical
fiber bores; and at least one force centering element for applying
a biasing force to the ferrule in the direction of the longitudinal
axis without generating a moment about a lateral axis defined by
the end face of the ferrule wherein the end face defines a first
lateral axis generally perpendicular to the longitudinal axis; and
wherein the rear face comprises the at least one force centering
element.
10. (canceled)
11. A fiber optic connector according to claim 9 wherein the end
face further defines a second lateral axis generally perpendicular
to the longitudinal axis and to the first lateral axis and wherein
the rear face defines a first convex surface in the direction of
the first lateral axis and a second convex surface in the direction
of the second lateral axis.
12. A fiber optic connector according to claim 5 wherein the end
face defines a first lateral axis generally perpendicular to the
longitudinal axis and wherein the forward portion of the spring
seat defines a convex surface in the direction of the first lateral
axis.
13. A fiber optic connector according to claim 5 wherein the end
face defines a first lateral axis generally perpendicular to the
longitudinal axis and a second lateral axis generally perpendicular
to the longitudinal axis and to the first lateral axis and wherein
the forward portion of the spring seat defines a convex surface in
the direction of the second lateral axis.
14. A fiber optic connector according to claim 5 wherein the end
face defines a first lateral axis generally perpendicular to the
longitudinal axis and a second lateral axis generally perpendicular
to the longitudinal axis and to the first lateral axis and wherein
the forward portion of the spring seat defines a first convex
surface in the direction of the first lateral axis and a second
convex surface in the direction of the second lateral axis.
15. A fiber optic connector comprising: a multifiber ferrule having
an end face and an opposed rear face, the end face defining a
plurality of optical fiber bores opening therethrough for receiving
respective optical fibers, the fiber optic connector defining a
longitudinal axis that is generally parallel to each of the optical
fiber bores; and at least one force centering element for applying
a biasing force to the ferrule in the direction of the longitudinal
axis without generating a moment about a lateral axis defined by
the end face of the ferrule; and a spring seat having a forward
portion for engaging the rear face of the ferrule and a rearward
portion opposite the forward portion; and wherein the ferrule
comprises at least one first force centering element disposed on an
exterior surface of the ferrule medially between the end face and
the rear face.
16. A fiber optic connector according to claim 15 wherein the
spring seat comprises at least one second force centering element
disposed on the rearward portion.
17. A fiber optic connector according to claim 16 wherein the
spring seat further comprises at least one transfer arm extending
outwardly from the forward portion for engaging the at least one
first force centering element.
18. A fiber optic connector according to claim 16 wherein the at
least one second force centering element engages a coil spring that
exerts the biasing force on the ferrule and wherein the transfer
arm transfers a portion of the biasing force to the at least one
first force centering element.
19. A fiber optic connector according to claim 16 wherein the end
face defines a first lateral axis perpendicular to the longitudinal
axis and a second lateral axis perpendicular to the longitudinal
axis and to the first lateral axis and wherein the at least one
first force centering element comprises a pair of first force
centering elements spaced apart laterally in the direction of the
second lateral axis and symmetrical about a plane comprising the
second lateral axis and the longitudinal axis.
20. A fiber optic connector according to claim 16 wherein the end
face defines a first lateral axis perpendicular to the longitudinal
axis and a second lateral axis perpendicular to the longitudinal
axis and to the first lateral axis and wherein the at least one
second force centering element comprises a pair of second force
centering elements spaced apart laterally in the direction of the
first lateral axis and symmetrical about a plane comprising the
first lateral axis and the longitudinal axis.
21-30. (canceled)
31. A fiber optic connector comprising: a multifiber ferrule having
an end face and an opposed rear face, the ferrule having a
plurality of optical fiber bores extending therethrough and opening
on the end face for receiving respective optical fibers therein,
the fiber optic connector defining a longitudinal axis that is
generally parallel to each of the optical fiber bores; a spring
seat having a forward portion for engaging the rear face of the
ferrule and a rearward portion opposite the forward portion; at
least one first force centering element for applying a resultant
biasing force in the direction of the longitudinal axis such that
the ferrule is not subjected to a moment about a first lateral axis
defined by the end face of the ferrule that is generally
perpendicular to the longitudinal axis; and at least one second
force centering element for applying a resultant biasing force to
the ferrule in the direction of the longitudinal axis such that the
ferrule is not subjected to a moment about a second lateral axis
defined by the end face of the ferrule that is generally
perpendicular to the longitudinal axis and to the first lateral
axis.
32. A multifiber ferrule for a fiber optic connector, the ferrule
comprising: a ferrule body extending between an end face and an
opposed rear face, the ferrule body having a plurality of optical
fiber bores opening through the end face, the end face defining a
first lateral axis in a first direction and a second lateral axis
in a second direction generally perpendicular to the first
direction; wherein the rear face of the ferrule body comprises at
least one force centering element for ensuring that a biasing force
exerted on the ferrule does not subject the ferrule body to a
moment about the first lateral axis and does not subject the
ferrule body to a moment about the second lateral axis.
33. A multifiber ferrule according to claim 32 wherein the at least
one force centering element comprises an outwardly extending
protrusion.
34. A multifiber ferrule according to claim 32 wherein the at least
one force centering element comprises a first convex surface in the
first direction.
35. A multifiber ferrule according to claim 32 wherein the at least
one force centering element comprises a second convex surface in
the second direction.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to fiber optic
connectors, and more particularly, to a fiber optic connector
including a multifiber ferrule and means for applying an axial
biasing force to the ferrule.
[0002] The proliferation of optical communications and data
transfer has dramatically increased the use of fiber optic
connectors including multifiber ferrules for simultaneously
interconnecting a plurality of optical fibers. Not only are
multifiber connectors being utilized in greater numbers, but
increased performance demands are being placed upon the optical
connections between mated connectors. As a result, there is an
increased demand in optical communications for what has become
generally known as "low-loss, intermateable, multifiber
connectors." For example, in order to maximize signal transmission
between pairs of opposed optical fibers, multifiber connectors are
required to align each of the optical fibers very precisely,
especially for single mode applications. In this regard, multifiber
connectors are typically required to align each optical fiber to
within about 7 to 14 microns for multimode applications and to
within about 0 to 3 microns for single mode applications.
[0003] In order to provide the desired alignment, conventional
multifiber ferrules define a pair of elongate alignment holes that
receive and cooperate with respective alignment members, such as
guide pins, to accurately align opposing ferrules, and in turn, the
optical fibers mounted within the multifiber ferrules. For example,
one conventional type of multifiber ferrule is the MT (Mechanically
Transferable) ferrule, such as described by U.S. Pat. No. 5,214,830
to Sinji Nagasawa, et al., and assigned to Nippon Telephone and
Telegraph Corporation of Tokyo, Japan. The MT ferrule has a
generally rectangular shape in lateral cross-section and defines a
pair of guide pin holes and a plurality of optical fiber bores
opening through the end face of the ferrule. The guide pin holes
receive respective guide pins to align the optical fibers of a pair
of opposing MT ferrules.
[0004] The pair of MT ferrules that are to be interconnected are
typically configured such that one of the multifiber connectors has
a male configuration and the other multifiber connector has a
female configuration. The male configuration of the multifiber
connector includes a pair of guide pins that have been inserted
within the guide pin holes defined by the MT ferrule and extend
forwardly beyond the end face. In contrast, the female
configuration of the multifiber connector includes an MT ferrule
that defines a pair of guide pin holes for receiving the portions
of the guide pins that extend beyond the end face of the male MT
ferrule. During mating, insertion of the guide pins into the guide
pin holes defined by the female MT ferrule aligns the male and
female connectors, and in turn, aligns the optical fibers mounted
within the MT ferrules. In order to snugly receive the guide pins,
the guide pin holes defined by a conventional MT ferrule are
cylindrical in lateral cross-section so as to have the same size
and shape along their entire length. By utilizing cylindrical guide
pin holes, the sidewalls of the guide pin holes contact the guide
pins along their entire length, thereby maximizing the alignment
provided by the guide pins.
[0005] The MT ferrules of the male and female fiber optic
connectors are biased towards one another so as to interconnect the
optical fibers with a minimum amount of attenuation. It has long
been believed that "dry physical contact" (i.e., physical contact
between opposing optical fibers without the use of index-matching
gel) across all of the pairs of optical fibers of mated multifiber
connectors could be achieved by controlling the geometry of the
opposing optical fibers and ferrules. However, significant advances
in geometry control, such as optimal fiber height, array
uniformity, optical fiber angle, core dip and ferrule end face
angle, have not consistently resulted in dry physical contact
across all of the optical fibers of opposing multifiber connector
pairs. Further analysis of the factors preventing dry physical
contact of the optical fibers has shown that the force applied to
bias the ferrule in the axial direction of the mating ferrule very
often produces a moment about a lateral axis of the ferrule. In
other words, the biasing force is not always applied along the
longitudinal axis of the ferrule, or at the least, is not balanced
about the longitudinal axis of the ferrule.
[0006] Typically, the biasing force is generated by a coil spring
mounted within a connector housing between the rear face of the
ferrule and a spring push. An off-axis biasing force oftentimes
results because the coil spring buckles within the connector
housing and introduces a component of the spring force that is
offset from the longitudinal axis of the ferrule, or is applied at
an angle other than normal to the end face of the ferrule. Even if
the coil spring does not buckle, the geometry and inherent nature
of the coil spring makes it likely that an unbalanced biasing force
will be applied to the rear face of the ferrule in a direction
other than along the longitudinal axis. As a result, the biasing
force will apply an undesired moment to the ferrule in addition to
the desired axial force. Thus, despite the presence of
substantially perfect geometry features in mating optical fibers
and ferrules, a biasing force that is not applied along the
longitudinal axis of a multifiber ferrule, or is not balanced about
the longitudinal axis of a multifiber ferrule, will not
consistently produce dry physical contact between a mated pair of
fiber optic connectors.
SUMMARY OF THE INVENTION
[0007] The above described and other deficiencies of conventional
fiber optic connectors are addressed and overcome by a fiber optic
connector according to the present invention that includes a
multifiber ferrule and force centering means for applying an axial
biasing force to the ferrule.
[0008] In one advantageous embodiment, a fiber optic connector
includes a multifiber ferrule having an end face and an opposed
rear face. The end face defines a plurality of optical fiber bores
opening therethrough for receiving respective optical fibers and
the fiber optic connector defines a longitudinal axis that is
generally parallel to each of the optical fiber bores. The fiber
optic connector further includes at least one force centering
element for applying a biasing force to the ferrule in the
direction of the longitudinal axis without generating a moment
about a lateral axis defined by the end face of the ferrule. The
fiber optic connector further includes a coil spring and a spring
seat disposed between the coil spring and the ferrule. The spring
seat has a forward portion that engages the rear face of the
ferrule and a rearward portion opposite the forward portion. The at
least one force centering element is disposed medially on the
rearward portion of the spring seat in the form of a protrusion
that extends outwardly from the rearward portion. The protrusion
engages the coil spring that exerts the biasing force on the
ferrule and the forward portion engages the rear face of the
ferrule to transfer the biasing force to the ferrule.
Alternatively, the protrusion may be disposed medially on the
forward portion of the spring seat that engages the rear face of
the ferrule. The spring seat may also have an arcuate side wall for
engaging an interior surface of a connector housing such that the
spring seat is movable only in the direction of the longitudinal
axis.
[0009] In another advantageous embodiment, a fiber optic connector
includes a multifiber ferrule having an end face and an opposed
rear face. The end face defines a plurality of optical fiber bores
opening therethrough for receiving respective optical fibers and
the fiber optic connector defines a longitudinal axis that is
generally parallel to each of the optical fiber bores. The fiber
optic connector further includes at least one force centering
element for applying a biasing force to the ferrule in the
direction of the longitudinal axis without generating a moment
about a lateral axis defined by the end face of the ferrule. The
fiber optic connector further includes a coil spring and a spring
seat disposed between the coil spring and the ferrule. The end face
of the ferrule defines a first lateral axis generally perpendicular
to the longitudinal axis and the rear face defines a convex surface
in the direction of the first lateral axis. The end face of the
ferrule may further define a second lateral axis generally
perpendicular to the longitudinal axis and to the first lateral
axis and the rear face may further define a convex surface in the
direction of the second lateral axis. Alternatively, the forward
portion of the spring seat may define a convex surface in the
direction of the first lateral axis and may further define a convex
surface in the direction of the second lateral axis.
[0010] In another advantageous embodiment, a fiber optic connector
includes a multifiber ferrule having an end face and an opposed
rear face. The end face defines a plurality of optical fiber bores
opening therethrough for receiving respective optical fibers and
the fiber optic connector defines a longitudinal axis that is
generally parallel to each of the optical fiber bores. The fiber
optic connector further includes at least one force centering
element for applying a biasing force to the ferrule in the
direction of the longitudinal axis without generating a moment
about a lateral axis defined by the end face of the ferrule. The
fiber optic connector further includes a coil spring and a spring
seat disposed between the coil spring and the ferrule. The spring
seat has a forward portion for engaging the rear face of the
ferrule and a rearward portion opposite the forward portion for
engaging the coil spring. The ferrule is provided with at least one
first force centering element disposed on an exterior surface of
the ferrule medially between the end face and the rear face, and
the spring seat is provided with at least one second force
centering element disposed on the rearward portion. The spring seat
may further have at least one transfer arm extending outwardly from
the forward portion for transferring a portion of the biasing force
to the at least one first force centering element on the ferrule.
The end face of the ferrule further defines a first lateral axis
perpendicular to the longitudinal axis and a second lateral axis
perpendicular to the longitudinal axis and to the first lateral
axis. Preferably, the ferrule is provided with a pair of first
force centering elements spaced apart laterally in the direction of
the second lateral axis and symmetrical about a plane comprising
the second lateral axis and the longitudinal axis. Preferably, the
spring seat is provided with a pair of second force centering
elements spaced apart laterally in the direction of the first
lateral axis and symmetrical about a plane comprising the first
lateral axis and the longitudinal axis.
[0011] In another advantageous embodiment, a fiber optic connector
includes a multifiber ferrule having an end face and an opposed
rear face. The ferrule further has a plurality of optical fiber
bores extending therethrough for receiving the end portions of
respective optical fibers adjacent the end face and at least one
guide pin hole for receiving a guide pin to align the multifiber
ferrule with a mating multifiber ferrule. The guide pin hole
defines an axis that is parallel to each of the optical fiber bores
and the fiber optic connector defines a longitudinal axis that is
generally parallel to the axis defined by the guide pin hole. The
fiber optic connector further includes at least one force centering
element for applying a resultant biasing force to the ferrule in
the direction of the longitudinal axis such that the ferrule is not
subjected to a moment about a lateral axis defined by the end face
of the ferrule and generally perpendicular to the longitudinal
axis.
[0012] In another advantageous embodiment, a multifiber ferrule is
movably disposed within a fiber optic connector. The multifiber
ferrule has an end face, an opposed rear face and a plurality of
optical fiber bores extending between the end face and the rear
face. The optical fiber bores open through the end face and the end
face defines a plane that is generally perpendicular to each of the
optical fiber bores. The multifiber ferrule further includes force
centering means for exerting a biasing force on the ferrule such
that the ferrule moves only in an axial direction that is parallel
to each of the optical fiber bores and does not produce a moment
about a lateral axis in the plane defined by the end face. The
force centering means may be provided in the form of a coil spring
and a spring seat disposed between the coil spring and the ferrule
with a forward portion of the spring seat engaging the rear face of
the ferrule and a rearward portion of the spring seat engaging the
coil spring opposite the forward portion.
[0013] In another advantageous embodiment, a multifiber ferrule for
a fiber optic connector includes a ferrule body extending between
an end face and an opposed rear face. The ferrule body has a
plurality of optical fiber bores opening through the end face. The
end face defines a first lateral axis in a first direction and a
second lateral axis in a second direction generally perpendicular
to the first direction. The rear face of the ferrule body defines a
first convex surface in the first direction and a second convex
surface in the second direction. Preferably, the radius of
curvature of the first convex surface in the first direction is
smaller than the radius of curvature of the second convex surface
in the second direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above described and other features, aspects, and
advantages of the present invention are better understood when the
following detailed description of the invention is read with
reference to the accompanying drawings, wherein:
[0015] FIG. 1 is an exploded perspective view of a fiber optic
connector according to an exemplary embodiment of the present
invention;
[0016] FIG. 2 is a perspective view of the force centering assembly
of the fiber optic connector shown in FIG. 1 illustrating the
multifiber ferrule, the spring seat and the coil spring;
[0017] FIG. 3 is a top view of the force centering assembly shown
in FIG. 2;
[0018] FIG. 4 is a rear end view of the force centering assembly
shown in FIG. 2 with the coil spring removed for purposes of
clarity;
[0019] FIG. 5 is a perspective view of a fully assembled fiber
optic connector according to another exemplary embodiment of the
present invention;
[0020] FIG. 6 is a lengthwise cross-sectional view of the fiber
optic connector shown in FIG. 5 taken along the line 6-6 in FIG.
5;
[0021] FIG. 7 is an exploded perspective view of the force
centering assembly of the fiber optic connector shown in FIG. 5
illustrating the multifiber ferrule, a guide pin, the pin keeper,
the spring seat, the coil spring and the lead-in tube;
[0022] FIG. 8 is an exploded perspective view of a fiber optic
connector according to yet another exemplary embodiment of the
present invention;
[0023] FIG. 9 is a perspective view of the force centering assembly
of the fiber optic connector shown in FIG. 8 illustrating the
multifiber ferrule, the guide pins, the pin keeper, the spring seat
and the coil spring;
[0024] FIG. 10 is a top view of the force centering assembly shown
in FIG. 9;
[0025] FIG. 11 is a side view of the force centering assembly shown
in FIG. 9;
[0026] FIG. 12 is an exploded perspective view of a fiber optic
connector according to yet another exemplary embodiment of the
present invention;
[0027] FIG. 13 is a partial top view of the force centering
assembly of the fiber optic connector shown in FIG. 12 illustrating
a portion of the multifiber ferrule, the spring seat and the coil
spring;
[0028] FIG. 14 is an exploded perspective view of a fiber optic
connector according to a dual axis embodiment of the present
invention;
[0029] FIG. 15 is a perspective view of the fully assembled fiber
optic connector shown in FIG. 14 with a portion of the connector
housing removed for purposes of clarity;
[0030] FIG. 16 is an exploded perspective view of the force
centering assembly of the fiber optic connector shown in FIG. 14
illustrating the multifiber ferrule, the guide pins, the pin keeper
and the dual axis spring seat with the coil spring removed for
purposes of clarity;
[0031] FIG. 17 is a perspective view of the fully assembled force
centering assembly shown in FIG. 16;
[0032] FIG. 18 is a top view of the force centering assembly shown
in FIG. 17; and
[0033] FIG. 19 is a rear end view of the force centering assembly
shown in FIG. 17 with the coil spring removed for purposes of
clarity.
DETAILED DESCRIPTION OF THE INVENTION
[0034] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
exemplary embodiments of the invention are shown, including the
embodiment presently contemplated by the inventors as being the
best mode of practicing the claimed invention. The invention may,
however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Instead,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like reference numbers refer
to like elements throughout the detailed description and the
various drawings.
[0035] Referring now to the accompanying drawings, FIGS. 1-4 show a
fiber optic connector 20 according to an exemplary embodiment of
the present invention. The illustrated embodiment of the connector
20 comprises an MT-type multifiber ferrule 30 having a ferrule body
32 that is generally rectangular in lateral cross-section. Although
an MT-style ferrule is illustrated and described herein, the
multifiber ferrule 30 need not be an MT-type ferrule and may be any
other type of multifiber ferrule. Regardless of the type, the
ferrule 30 extends lengthwise within the connector 20 between an
end face 34 and an opposed rear face 36. In addition, the ferrule
body 32 defines a plurality of bores 38 opening through the end
face 34. The bores 38 are arranged in a laterally extending linear
row for receiving the end portions of respective optical fibers.
Although the embodiments of the multifiber ferrule 30 illustrated
herein define a total of twelve bores 38 such that the multifiber
ferrule 30 can be mounted upon the end portions of twelve
individual optical fibers, the end face 34 may define any number of
bores, such as 2, 4, 6, 8, 10 or more. In addition, the multifiber
ferrule 30 may comprise more than a single linear row of bores 38.
Furthermore, the bores 38 need not be arranged in one or more
laterally extending linear rows. For example, any number of bores
38 may be arranged in any predetermined pattern on the end face 34
of the ferrule 30.
[0036] The ferrule body 32 may also define at least one elongate
guide pin hole 40 (FIG. 2) also referred to in the art as an
alignment hole. The guide pin hole 40 opens through the end face 34
and is adapted to receive a respective guide pin 42 to align the
ferrule 30 with an opposing ferrule of a mating connector in a
known manner. In the exemplary embodiments shown herein, the
multifiber ferrule 30 is an MT-type ferrule and the ferrule body 32
at least partially defines at least one and, more typically, a pair
of guide pin holes 40 for receiving respective guide pins 42.
Regardless of the type of ferrule 30, each elongate guide pin hole
40 defined by the ferrule body 32 in turn defines a longitudinal
axis 50 (FIG. 2) extending through the center of the guide pin hole
40. The ferrule 30 is manufactured such that the longitudinal axis
50 of each guide pin hole 40 is precisely parallel to the bores 38
extending lengthwise through the ferrule body 32 and perpendicular
to the end face 34. As illustrated in FIG. 1, the connector 20 has
a male configuration because the ferrule 30 is provided with a pair
of guide pins 42 and a guide pin retainer, or pin keeper, 44. The
pin keeper 44 is positioned adjacent the rear face 36 of the
ferrule body 32, as will be described, to secure the guide pins 42
within the guide pin holes 40. The guide pins 42 are secured such
that their free ends protrude forwardly from the end face 34 of the
ferrule body 32 a sufficient distance to engage the guide pin holes
40 of the ferrule of a mating connector, thereby aligning the
optical fibers mounted within the respective bores 38 of the
opposing ferrules. As is known, the free ends of the guide pins 42
may be tapered and/or the guide pins holes 40 may be provided with
a lead-in chamfer to facilitate insertion of the guide pins 42 into
the guide pin holes 40 and to reduce pin stubbing and/or damage to
the end face 34 during mating of the opposing ferrules.
[0037] As illustrated herein, the connector 20 further comprises a
spring seat 60, a coil spring 70, a spring push 80, a lead-in tube
90 and a generally hollow connector housing 100. The various
components of the connector 20 and their functions are generally
known. Thus, each component will not be described in detail herein
except as necessary to enable one of ordinary skill in the art to
understand and fully appreciate the present invention. Furthermore,
it will be readily understood by those skilled in the art that each
of the components may be configured in any number of different
shapes, sizes and constructions without departing from the intended
scope of the invention, as defined by the appended claims.
Regardless, the spring seat 60 of the exemplary embodiment shown in
FIG. 1 is positioned adjacent the rear face 36 of the ferrule body
32 between the ferrule 30 and the coil spring 70. An opening 62
extending lengthwise through the spring seat 60 permits the lead-in
tube 90 and the end portions of the optical fibers (not shown) to
pass through the spring seat 60 to the rear face 36 of the ferrule
30. The spring seat 60 comprises a forward portion 64 for engaging
and retaining the pin keeper 44 between the spring seat 60 and the
ferrule 30, and thereby securing the guide pins 42 within the guide
pin holes 40 of the ferrule 30. As best shown in FIG. 3, the spring
seat 60 further comprises a rearward portion 66 for receiving the
coil spring 70 thereon. In particular, the rearward portion 66 of
the spring seat 60 defines at least one force centering element 68
that engages the forward most coil of the coil spring 70, as will
be described in greater detail hereinafter.
[0038] The coil spring 70 is positioned between the spring seat 60
and the spring push 80. An opening 72 extending lengthwise through
the coil spring 70 permits the lead-in tube 90 and the end portions
of the optical fibers (not shown) to pass through the coil spring
70 to the rear face 36 of the ferrule 30. In the fiber optic
connector 20 described and shown herein, the coil spring 70 is a
conventional helical spring having dead coils with ground ends in
certain embodiments and open coils in other embodiments. The
compressive force of the coil spring 70 may vary depending on the
type of fiber optic connector and multifiber ferrule, but
preferably is in the range of about 9-11 Newtons. The spring push
80 comprises a forward portion 84 for engaging the rearward most
coil of the coil spring 70, and thereby retaining the coil spring
70 against the force centering element 68 defined by the spring
seat 60. The spring push 80 further comprises a rearward portion 86
that defines a crimp body 87 for securing the strength members of a
fiber optic cable (not shown) to the spring push 80 in a known
manner. An opening 82 extending lengthwise through the spring push
80 permits the lead-in tube 90 and the end portions of the optical
fibers (not shown) to pass through the spring push 80 to the rear
face 36 of the ferrule 30. The lead-in tube 90 is positioned within
the opening 82 of the spring push 80, the opening 72 of the coil
spring 70 and the opening 62 of the spring seat 60. An opening 92
extending lengthwise through the lead-in tube 90 receives and
guides the end portions of the optical fibers of the fiber optic
cable into the respective bores 38 of the ferrule 30. Finally, the
ferrule 30 and guide pins 42, the pin keeper 44, the spring seat
60, the coil spring 70, the forward portion 84 of the spring push
80 and the lead-in tube 90 are positioned within a connector
housing 100. Flexible arms 88 provided on spring push 80 depend
lengthwise from the forward portion 84 to engage openings 102
formed in the connector housing 100 to secure the spring push 80 to
the connector housing 100. A forward mechanical stop (not shown) is
provided on the interior surface of the connector housing 100 in a
known manner so that the ferrule 30 is movably disposed within the
connector housing 100, but is biased in the forward direction by
the coil spring 70 and the spring seat 60.
[0039] When a pair of fiber optic connectors 20 is mated, the
opposing ferrules 30 are typically brought into physical contact
with one another so that the coil springs 70 each exert a biasing
force on the respective ferrule 30. As a result, the end faces 34
of the opposing ferrules 30 and/or the opposing optical fibers are
pressed into physical engagement and biased against one another.
Because the coil spring and the ferrule are not constrained to move
only in the axial direction within the connector housing, it is
possible that the resultant biasing force exerted by a coil spring
in a conventional fiber optic connector will not be entirely in the
axial direction. As a result, the ferrule may rotate about one or
both of the lateral axes X, Y defined by the end face 34 of the
ferrule 30 shown in FIG. 2. For example, the coil spring 70 may
buckle slightly and cause the biasing force to be concentrated
along one of the edges of the spring seat 60. The unbalanced
biasing force causes a moment to be applied to the ferrule body 32
about the corresponding lateral axis X, Y, which results in the end
face 34 of the ferrule 30 having an angle other than normal
relative to the longitudinal axis Z defined by the connector. If
the end face 34 of the ferrule 30 is rotated about one or both of
the lateral axes X, Y, certain of the opposing optical fibers may
lose physical contact with one another, thereby creating a gap
between the optical fibers that introduces back reflection and
attenuation loss. Because the plurality of optical fibers are
spaced apart in the direction of the lateral axis X in the
illustrated embodiments, rotation of the ferrule body 32 about the
lateral axis Y is significantly more critical than rotation of the
ferrule body 32 about the lateral axis X. Specifically, separation
between the opposing optical fibers will increase in the direction
of rotation such that a substantial separation may occur between
the outermost pair of opposing optical fibers. However, it will be
readily apparent to one of ordinary skill in the art that rotation
of the ferrule body about the lateral axis X can cause a
significant increase in the back reflection and attenuation loss
between opposing optical fibers in a mated pair of fiber optic
connectors comprising multifiber ferrules having multiple rows of
optical fibers.
[0040] In the present invention, a fiber optic connector comprising
a multifiber ferrule is provided with means for applying a biasing
force along the longitudinal axis Z defined by the connector. In
particular, a biasing force is applied to the ferrule body that is
balanced about one or both of the lateral axes X, Y defined by the
end face of the ferrule. As used herein, the term "force centering
means" refers to the combination of structural elements that cause
the resultant biasing force exerted by the coil spring on the
ferrule body to be applied along the longitudinal axis Z defined by
the connector. The term "axial biasing force" refers to a resultant
biasing force exerted by the coil spring that is applied along the
longitudinal axis Z defined by the connector. FIGS. 2-4 illustrate
the force centering means of the fiber optic connector 20 shown in
FIG. 1. In particular, FIGS. 2-4 illustrate the structural elements
of the fiber optic connector 20 that combine to ensure that the
coil spring 70 exerts a resultant axial biasing force on the
ferrule 30 along the longitudinal axis Z of the connector so that
the ferrule body 32 does not rotate about one or both of the
lateral axes X, Y in the lateral plane defined by the end face 34.
In the exemplary embodiment shown in FIGS. 1-4, the spring seat 60
is provided with at least one, and preferably a pair, of force
centering elements 68 located medially on opposite sides of the
rearward portion 66. The force centering elements 68 engage the
forward most helical coil of the coil spring 70 and are arranged
symmetrical to the longitudinal plane defined by the lateral axis Y
and the longitudinal axis Z. Thus, any moment about the lateral
axis Y introduced by the biasing force exerted by the coil spring
70 on the spring seat 60 and transferred to the ferrule 30 is
minimized. Preferably, the biasing force is balanced about the
lateral axis Y so that the resultant biasing force is aligned with
the longitudinal axis Z. The force centering elements 68 are also
located at equal distances on the rearward portion 66 of the spring
seat 60 from the plane defined by the lateral axis X and the
longitudinal axis Z. Thus, the biasing force exerted by the coil
spring 70 on the spring seat 60 and transferred to the ferrule 30
is balanced about the lateral axis X so that the resultant biasing
force is aligned with the longitudinal axis Z. As a result, an
axial biasing force is applied to the multifiber ferrule 30 and the
end face 34 does not rotate about one or both of the lateral axes
X, Y normal to the longitudinal axis Z defined by the fiber optic
connector 20.
[0041] FIGS.5-7 show another exemplary embodiment of a fiber optic
connector 120 according to the present invention. The connector 120
comprises a ferrule 30, at least one guide pin 42 received within a
guide pin hole 40 opening through the end face 34 of the ferrule
30, a coil spring 70, a spring push 80 and a connector housing 100,
that are configured substantially as previously described.
Accordingly, the substantially similar components indicated by the
like reference numbers will not be described in greater detail,
except as necessary to explain the present exemplary embodiment.
The connector 120 further comprises a pin keeper 144, a spring seat
160 and a lead-in tube 190 that are configured somewhat different
than the pin keeper 44, spring seat 60 and lead-in tube 90
previously described in connection with the fiber optic connector
20. In particular, the pin keeper 144 is adapted to be received
within a recess formed in the forward portion 164 of the spring
seat 160 such that the pin keeper 144 is retained between the rear
face 36 of the ferrule 30 and the forward portion 164 of the spring
seat 160. The pin keeper 144 engages the ends of the guide pin(s)
42 as previously described to secure the guide pin(s) 42 within the
guide pin hole(s) 40 extending lengthwise through the ferrule body
32. The lead-in tube 190 serves as a replacement for the lead-in
tube 90 previously described and comprises a forward portion 194
that is shaped and configured to engage the rear face 36 of the
ferrule body 32 in a slight interference fit. An opening 192
extending lengthwise through the lead-in tube 190 receives and
guides the end portions of the optical fibers of the fiber optic
cable into the respective bores 38 of the ferrule 30.
[0042] The spring seat 160 comprises a forward portion 164 adjacent
the rear face 36 of the ferrule 30 and a rearward portion 166
opposite the forward portion 164 and adjacent the coil spring 70.
An opening 162 extending lengthwise through the spring seat 160
allows the forward portion 194 of the lead-in tube 190 to pass
through the spring seat 160 to the rear face 36 of the ferrule body
32. The opening 162 also receives the coil spring 70 therein such
that the forward most helical coil of the coil spring 70 engages a
shelf provided on the periphery of the spring seat 160 adjacent the
rearward portion 166. At least one, and preferably a pair, of force
centering elements 168 is also provided on the spring seat 160
adjacent the forward portion 164. Although shown herein on the
forward portion 164 of the spring seat 160, one of ordinary skill
will readily appreciate that the force centering elements 168
alternatively may be provided on the rear face 36 of the ferrule
body 32. Similar to the pair of force centering elements 68
previously described, the force centering elements 168 are arranged
symmetrical to the longitudinal plane defined by the lateral axis Y
and the longitudinal axis Z. Thus, any moment about the lateral
axis Y introduced by the biasing force exerted by the coil spring
70 on the spring seat 160 and transferred to the ferrule 30 is
minimized. Preferably, the biasing force is balanced about the
lateral axis Y so that the resultant biasing force is aligned with
the longitudinal axis Z. Unlike the force centering elements 68,
the force centering elements 168 of the spring seat 160 engage the
rear face 36 of the ferrule body 32 directly (instead of the
forward most helical coil of the coil spring 70). Thus, the force
centering elements 168 are located closer to the end face 34 of the
ferrule 30. As a result, the longitudinal distance between the
location at which the biasing force is applied (i.e., the rear face
36 of the ferrule body 32) and the end face 34 of the ferrule 30 is
substantially reduced. Accordingly, any moment introduced by the
biasing force about the lateral axis Y is further reduced. The
force centering elements 168 are also located at equal distances on
the forward portion 164 of the spring seat 160 from the plane
defined by the lateral axis X and the longitudinal axis Z. Thus,
the biasing force exerted by the coil spring 70 on the spring seat
160 and transferred directly to the ferrule 30 is balanced about
the lateral axis X so that the resultant biasing force is aligned
with the longitudinal axis Z. As a result, an axial biasing force
is applied to the multifiber ferrule 30 and the end face 34 does
not rotate about one or both of the lateral axes X, Y normal to the
longitudinal axis Z defined by the fiber optic connector 120. As
best shown in the view FIG. 6, the spring seat 160 is provided with
lateral exterior side walls 165 that are arcuate in shape in the
direction of the longitudinal axis Z. The arcuate side walls 165
engage the lateral interior side walls 105 of the connector housing
100 so that the spring seat 160 is constrained against lateral
movement, while at the same time being permitted to move forward
and rearward in the axial direction (i.e., longitudinally). Because
of the pivoting function of the force centering elements 168 and
the sliding function of the side walls 165, the spring seat 160 of
the fiber optic connector 120 is also referred to as a "piston
rocker" spring seat.
[0043] FIGS. 8-11 show yet another exemplary embodiment of a fiber
optic connector 220 according to the present invention. The
connector 220 comprises at least one guide pin 42, a coil spring
70, a spring push 80, a lead-in tube (not shown) and a connector
housing 100 that are configured substantially as previously
described. Accordingly, the substantially similar components
indicated by the like reference numbers will not be described in
greater detail, except as necessary to explain the present
exemplary embodiment. The connector 220 further comprises a ferrule
230 having at least one guide pin hole 240 opening through the end
face 234 of the ferrule body 232 for receiving the guide pin(s) 42,
a pin keeper 244 and a spring seat 260 that are configured somewhat
different than the ferrule 30, the pin keepers 44 and 144, and the
spring seats 60 and 160 previously described in connection with the
fiber optic connectors 20 and 120. In particular, the ferrule body
232 comprises a slot 235 about its periphery adjacent the rear face
236 for receiving the pin keeper 244. The rear face 236 of the
ferrule body 232 has a convex shape in the direction of the lateral
axis X (FIG. 10) and a convex shape in the direction of the lateral
axis Y. As shown, the radius of curvature of the rear face 236 in
the direction of the lateral axis X is smaller than the radius of
curvature of the rear face 236 in the direction of the lateral axis
Y.
[0044] The rear face 236 of the ferrule body 232 engages the planar
forward portion 264 of the spring seat 260 and the planar rearward
portion 266 of the spring seat 260 engages the forward most helical
coil of the coil spring 70. Accordingly, the biasing force exerted
by the coil spring 70 on the spring seat 260 is transferred to the
convex-convex rear face 236 of the ferrule body 232. Similar to the
pair of force centering elements 68 and 168 previously described,
the rear face 236 of the ferrule 230 defines a pair of force
centering elements 268 that is arranged symmetrical to the
longitudinal plane defined by the lateral axis Y and the
longitudinal axis Z (FIG. 10). Thus, any moment about the lateral
axis Y introduced by the biasing force exerted by the coil spring
70 on the spring seat 260 and transferred to the ferrule 230 is
minimized. Preferably, the biasing force is balanced about the
lateral axis Y so that the resultant biasing force is aligned with
the longitudinal axis Z. The forward portion 264 of the spring seat
260 directly engages the force centering elements 268 on the rear
face 236 of the ferrule body 232. In addition, the force centering
elements 268 are located nearer in the longitudinal direction to
the end face 234 of the ferrule 230 than the coil spring 70.
Accordingly, any moment introduced by the biasing force about the
lateral axis Y or the lateral axis X is further reduced. The force
centering elements 268 are located at equal distances on the rear
face 236 of the ferrule body 232 from the plane defined by the
lateral axis X and the longitudinal axis Z (FIG. 11). Thus, the
biasing force exerted by the coil spring 70 on the spring seat 260
and transferred directly to the ferrule 230 is balanced about the
lateral axis X so that the resultant biasing force is aligned with
the longitudinal axis Z. As a result, an axial biasing force is
applied to the multifiber ferrule 230 and the end face 234 does not
rotate about one or both of the lateral axes X, Y normal to the
longitudinal axis Z defined by the fiber optic connector 220.
[0045] FIGS. 12 and 13 show yet another exemplary embodiment of a
fiber optic connector 320 according to the present invention. The
connector 320 comprises at least one guide pin 42, a pin keeper
244, a coil spring 70, a spring push 80, a lead-in tube (not shown)
and a connector housing 100 that are configured substantially as
previously described. Accordingly, the substantially similar
components indicated by the like reference numbers will not be
described in greater detail, except as necessary to explain the
present exemplary embodiment. The connector 320 further comprises a
ferrule 330 having at least one guide pin hole 340 opening through
the end face 334 of the ferrule body 332 for receiving the guide
pin(s) 42, and a spring seat 360 that are configured somewhat
different than the ferrules 30 and 230, and the spring seats 60,
160 and 260 previously described in connection with the fiber optic
connectors 20, 120 and 220. In particular, the ferrule body 332
comprises a slot 335 about its periphery adjacent the rear face 336
for receiving the pin keeper 244. The rear face 336 of the ferrule
body 332 defines a planar surface parallel to the end face 334,
while the forward portion 364 of the spring seat 360 has a convex
shape in the direction of the lateral axis X (FIG. 13) and a convex
shape in the direction of the lateral axis Y (not shown).
Preferably, the radius of curvature of the forward portion 364 in
the direction of the lateral axis X is smaller than the radius of
curvature of the forward portion 364 in the direction of the
lateral axis Y.
[0046] The planar rear face 336 of the ferrule body 332 engages the
convex-convex forward portion 364 of the spring seat 360 and the
planar rearward portion 366 of the spring seat 360 engages the
forward most helical coil of the coil spring 70. Accordingly, the
biasing force exerted by the coil spring 70 on the spring seat 360
is transferred to the convex-convex forward portion 364 of the
spring seat 360. Similar to the pair of force centering elements
68, 168 and 268 previously described, the forward portion 364 of
the spring seat 360 defines a pair of force centering elements 368
that is arranged symmetrical to the longitudinal plane defined by
the lateral axis Y and the longitudinal axis Z (FIG. 13). Thus, any
moment about the lateral axis Y introduced by the biasing force
exerted by the coil spring 70 on the spring seat 360 and
transferred to the ferrule 330 is minimized. Preferably, the
biasing force is balanced about the lateral axis Y so that the
resultant biasing force is aligned with the longitudinal axis Z.
The force centering elements 368 on the forward portion 364 of the
spring seat 360 directly engage the rear face 336 of the ferrule
body 332. In addition, the force centering elements 368 are located
nearer in the longitudinal direction to the end face 334 of the
ferrule 330 than the coil spring 70. Accordingly, any moment
introduced by the biasing force about the lateral axis Y or the
lateral axis X is further reduced. The force centering elements 368
are located at equal distances on the rear face 336 of the ferrule
body 332 from the plane defined by the lateral axis X and the
longitudinal axis Z. Thus, the biasing force exerted by the coil
spring 70 on the spring seat 360 and transferred directly to the
ferrule 330 is balanced about the lateral axis X so that the
resultant biasing force is aligned with the longitudinal axis Z. As
a result, an axial biasing force is applied to the multifiber
ferrule 330 and the end face 334 does not rotate about one or both
of the lateral axes X, Y normal to the longitudinal axis Z defined
by the fiber optic connector 320. In short, the locations of the
force centering elements and the respective functions of the
ferrule and the spring seat are reversed in the fiber optic
connector 320 (FIGS. 12 and 13) relative to the fiber optic
connector 220 (FIGS. 8-11).
[0047] FIGS. 14-19 show an exemplary embodiment of a dual axis
fiber optic connector 420 according to the present invention. The
connector 420 comprises at least one guide pin 42, a coil spring
70, a spring push (not shown), a lead-in tube (not shown) and a
connector housing 100 that are configured substantially as
previously described. Accordingly, the substantially similar
components indicated by the like reference numbers will not be
described in greater detail, except as necessary to explain the
present exemplary embodiment. The connector 420 further comprises a
ferrule 430 having at least one guide pin hole 440 opening through
the end face 434 of the ferrule body 432 for receiving the guide
pin(s) 42, a pin keeper 444 and a spring seat 460 that are
configured somewhat different than the ferrules 30, 230 and 330,
the pin keepers 44, 144 and 244, and the spring seats 60, 160 and
260 previously described in connection with the fiber optic
connectors 20, 120, 220 and 320. In particular, the ferrule body
432 comprises a pair of opposed slots 435 on its periphery adjacent
the rear face 436 for receiving the pin keeper 444. The ferrule 430
further comprises a pair of first force centering elements 468 on
the exterior surfaces of the ferrule body 432 in the direction of
the lateral axis Y that are disposed medially between the end face
432 and the rear face 436. As shown, the force centering elements
468 are disposed nearer to the end face 432 than the rear face 436,
for a purpose to be described. Each of the first force centering
elements 468 on the ferrule body 432 has a convex shape in the
direction of the lateral axis X (FIG. 18) that is disposed
rearwardly. As shown, the radius of curvature of the first force
centering elements 468 is substantially smaller than the radius of
curvature of the rear face 236 of the ferrule 230 in the direction
of the lateral axis X (FIG. 10) and the radius of curvature of the
forward portion 364 of the spring seat 360 in the direction of the
lateral axis X (FIG. 13).
[0048] The planar rear face 436 of the ferrule body 432 is received
within a recess 446 formed in the forward side of the pin keeper
444. The rearward side of the pin keeper 444 defines at least a
pair of spaced apart supports 448 for engaging the planar forward
portion 464 of the spring seat 460. Each of the supports 448
defines a slot 445 for engaging one end of the guide pin 42. The
rearward portion 466 of the spring seat 460 comprises a pair of
second force centering elements 469 that engage the forward most
helical coil of the coil spring 70. The second force centering
elements 469 are spaced apart in the direction of the lateral axis
X adjacent the periphery of the spring seat 460 and have a convex
shape in the direction of the lateral axis Y. As shown, the radius
of curvature of the convex second force centering elements 469 is
about the same as the radius of curvature of the convex first force
centering elements 468. Accordingly, a portion of the biasing force
exerted by the coil spring 70 on the spring seat 460 is transferred
to the pin keeper 444, and in turn, transferred to the ferrule body
432 through the slots 435. The spring seat 460 further comprises a
pair of transfer arms 465 that are laterally spaced apart in the
direction of the lateral axis Y and depend forwardly from the
forward portion 464 of the spring seat 460 through the pin keeper
444 to the first force centering elements 468. The free end of each
of the transfer arms 465 has a concave shape in the direction of
the lateral axis X (FIG. 18) that is disposed rearwardly. The
concave radius of curvature of the free ends of the transfer arms
465 is substantially the same as the convex radius of curvature of
the first force centering elements 468. Thus, the free ends of the
transfer arms 465 are configured to cooperate with the first force
centering elements 468, as will be described. Accordingly, the
remaining portion of the biasing force exerted by the coil spring
70 on the spring seat 460 is transferred through the transfer arms
465 to the first force centering elements 468.
[0049] Similar to the pair of force centering elements 68, 168, 268
and 368 previously described, the first pair of force centering
elements 468 is arranged symmetrical to the longitudinal plane
defined by the lateral axis Y and the longitudinal axis Z (FIG.
18). Thus, any moment about the lateral axis Y introduced by the
biasing force exerted by the coil spring 70 on the spring seat 460
and transferred through the transfer arms 465 to the ferrule 430 is
minimized. The convex radius of curvature of the first force
centering elements 468 and the corresponding concave radius of
curvature of the free ends of the transfer arms 465 cooperate to
ensure that the biasing force exerted by the coil spring 70 is
balanced about the lateral axis Y so that the resultant biasing
force is aligned with the longitudinal axis Z. The transfer arms
465 of the spring seat 460 directly engage the first force
centering elements 468 on the ferrule body 432 nearer in the
longitudinal direction to the end face 434 of the ferrule 430 than
the coil spring 70. Accordingly, any moment introduced by the
biasing force about the lateral axis Y or the lateral axis X is
further reduced. The first force centering elements 468 are located
at equal distances on the exterior surface of the ferrule body 432
from the plane defined by the lateral axis X and the longitudinal
axis Z. Thus, the biasing force exerted by the coil spring 70 on
the spring seat 460 and transferred directly to the ferrule 430 is
balanced about the lateral axis X so that the resultant biasing
force is aligned with the longitudinal axis Z. Similarly, the
second pair of force centering elements 469 is arranged symmetrical
to the longitudinal plane defined by the lateral axis X and the
longitudinal axis Z (FIG. 19). Thus, any moment about the lateral
axis X introduced by the biasing force exerted by the coil spring
70 on the spring seat 460 and transferred through the pin keeper
444 to the ferrule 430 is minimized. The convex radius of curvature
of the second force centering elements 469 ensures that the biasing
force exerted by the coil spring 70 is balanced about the lateral
axis X so that the resultant biasing force is aligned with the
longitudinal axis Z. The second force centering elements 469 are
located at equal distances on the rearward portion 466 of the
spring seat 460 from the plane defined by the lateral axis Y and
the longitudinal axis Z. Thus, the biasing force exerted by the
coil spring 70 on the spring seat 460 and transferred to the
ferrule 430 is balanced about the lateral axis Y so that the
resultant biasing force is aligned with the longitudinal axis Z. As
a result, an axial biasing force is applied to the multifiber
ferrule 430 and the end face 434 does not rotate about one or both
of the lateral axes X, Y normal to the longitudinal axis Z defined
by the fiber optic connector 420. Because the first force centering
elements 468 and the second force centering elements 469
simultaneously convert the biasing force exerted by the coil spring
70 on the ferrule 430 to an axial force in the direction of the
longitudinal axis Z, the fiber optic connector 420 is also referred
to as a "dual axis" force centering fiber optic connector.
[0050] Many modifications and other embodiments of the invention
will come to mind to one skilled in the art to which this invention
pertains having the benefit of the teachings presented in the
foregoing descriptions and the associated drawings. Therefore, it
is to be understood that the invention is not to be limited to the
specific embodiments disclosed herein and that modifications and
other embodiments are intended to be included within the scope of
the appended claims. Although specific terms have been employed
herein, they are used in a generic and descriptive sense only and
not for purposes of limitation.
* * * * *