Title: Optical and opto-electronic interconnect alignment system
Abstract: A connector alignment system includes a base for mounting on a first substrate, and a housing movably engaged with the base. The housing secures an opto-electronic termination. The housing has longitudinal, lateral, transverse and angular ranges of motion with respect to the base. When the housing is in an unmated position, various combinations of the lateral, transverse and angular ranges of motion are less than the respective ranges of motion when the housing is in a mated position.
Patent Number: 6,984,073 Issued on 01/10/2006 to Cox
| Inventors:
|
Cox; Larry R. (Austin, TX)
|
| Assignee:
|
3M Innovative Properties Company (St. Paul, MN)
|
| Appl. No.:
|
685149 |
| Filed:
|
October 14, 2003 |
| Current U.S. Class: |
385/55; 385/90 |
| Current Intern'l Class: |
G02B 6/38 (20060101) |
| Field of Search: |
385/53,54,55,88,89,90,92
|
References Cited [Referenced By]
U.S. Patent Documents
| 4890895 | Jan., 1990 | Zavracky et al.
| |
| 4899254 | Feb., 1990 | Ferchau et al.
| |
| 4944568 | Jul., 1990 | Danbach et al.
| |
| 5080461 | Jan., 1992 | Pimpinella.
| |
| 5138679 | Aug., 1992 | Edwards et al.
| |
| 5245683 | Sep., 1993 | Belenkiy et al.
| |
| 5542015 | Jul., 1996 | Hultermans.
| |
| 5692089 | Nov., 1997 | Sellers.
| |
| 5796896 | Aug., 1998 | Lee.
| |
| 5828807 | Oct., 1998 | Tucker et al.
| |
| 6196856 | Mar., 2001 | De Villeroche.
| |
| 6318902 | Nov., 2001 | Igl et al.
| |
| 6331079 | Dec., 2001 | Grois et al.
| |
| 6334784 | Jan., 2002 | Howard.
| |
| 6343171 | Jan., 2002 | Yoshimura et al.
| |
| 6358075 | Mar., 2002 | Tischner.
| |
| 6390690 | May., 2002 | Meis et al.
| |
| 6419399 | Jul., 2002 | Loder et al.
| |
| 6485192 | Nov., 2002 | Plotts et al.
| |
| 6535397 | Mar., 2003 | Clark et al.
| |
| 6540414 | Apr., 2003 | Brezina et al.
| |
| 6582133 | Jun., 2003 | Harris et al.
| |
| 6588943 | Jul., 2003 | Howard.
| |
| 2002/0094705 | Jul., 2002 | Driscoll et al.
| |
| 2002/0126960 | Sep., 2002 | Gurreri.
| |
| 2002/0180554 | Dec., 2002 | Clark et al.
| |
| 2002/0181883 | Dec., 2002 | Harris et al.
| |
| 2003/0068140 | Apr., 2003 | Brezina et al.
| |
| Foreign Patent Documents |
| WO 02/1698/9 | Feb., 2002 | WO.
| |
| WO 02/101436 | Dec., 2002 | WO.
| |
| WO 03/081311 | Oct., 2003 | WO.
| |
Other References
Shin'Ichi Iwano, et al., "Compact and Self-Retentive Multi-Ferrule Optical Backpanel
Connector", Journal of Lightwave Technology Oct. 10, 1992, No. 10, New York.
International Search Report for PCT/US2004/028867.
|
Primary Examiner: Le; Thanh-Tam
Attorney, Agent or Firm: Gover; Melanie G.
Claims
What is claimed is:
1. A fiber optic connector alignment system comprising:
a base configured for mounting on a first substrate; and
a housing movably engaged with the base by at least one channel on the housing
and at least one rail on the base, the housing configured to secure a terminating
ferrule for an optical fiber, a longitudinal orientation of the optical fiber within
the terminating ferrule defining a longitudinal axis, the housing movable along
the longitudinal axis between a mated position and an unmated position;
wherein the housing has a longitudinal range of motion and a lateral range of
motion, with respect to the base, in both the mated and unmated positions, wherein
the lateral range of motion when the housing is in the unmated position is less
than the lateral range of motion when the housing is in the mated position, and
wherein the channel and rail are engaged in both the mated and unmated positions.
2. The fiber optic connector alignment system of claim 1, further comprising
a spring element biasing the housing along the longitudinal axis toward the unmated position.
3. The fiber optic connector alignment system of claim 1, further comprising
a mating connector disposed on a second substrate and configured to mate with the housing.
4. The fiber optic connector alignment system of claim 1, wherein the housing
has an angular range of motion, and wherein the angular range of motion is reduced
when the housing is in the unmated position.
5. The fiber optic connector alignment system of claim 1, wherein the housing
is configured to secure a plurality of terminating ferrules.
6. The fiber optic connector alignment system of claim 1, wherein the housing
has a transverse range of motion, and wherein the transverse range of motion is
reduced when the housing is in the unmated position.
7. The fiber optic connector alignment system of claim 1, wherein the lateral
range of motion is in the range of 0.030 to 0.050 inches when the housing is in
the mated position.
8. The fiber optic connector alignment system of claim 1, wherein the lateral
range of motion is less than 0.010 inches when the housing is the unmated position.
9. The fiber optic connector alignment system of claim 1, wherein the rail is
shaped to restrict the lateral range of motion of the housing as the housing moves
longitudinally toward the unmated position.
10. The fiber optic connector alignment system of claim 9, wherein the rail is
shaped to restrict a transverse range of motion of the housing as the housing moves
longitudinally toward the unmated position.
11. The fiber optic connector alignment system of claim 9, wherein the housing
includes a pair of channels configured to engaged a pair of mating rails on the
base member.
12. The fiber optic connector alignment system of claim 1, wherein the housing
includes a tapered notch configured to engaged a smaller mating protrusion on the
base member, wherein a size difference between the tapered notch and the mating
protrusion decreases as the housing moves toward the unmated position.
13. A device for aligning a fiber optic connector on a first substrate with a
mating connector on a second substrate, the device comprising:
a base for securing to the first substrate having at least one rail;
a housing configured to hold a terminating ferrule and having at least one channel,
wherein the housing is slidably engaged with the base by the at least one channel
on the housing and the at least one rail on the base member to provide a longitudinal
range of motion and a lateral range of motion with respect to the base in both
mated and unmated positions; and
a spring element controlling movement of the housing along the longitudinal range
of motion;
wherein the lateral range of motion varies as the housing is moved through the
longitudinal range of motion, and wherein the at least one channel and the at least
one rail are engaged in both the mated and unmated positions.
14. The device of claim 13, wherein the spring element urges the housing to a
forward position, and wherein the lateral range of motion decreases as the housing
approaches the forward position.
15. The device of claim 14, wherein the lateral range of motion gradually decreases
as the housing approaches the forward position.
16. The device of claim 13, wherein the longitudinal range of motion comprises
a first portion and a second portion, and wherein the lateral range of motion varies
in the second portion.
17. The device of claim 16, wherein the housing has an angular range of motion
with respect to the base in the first portion of the longitudinal range of motion.
18. The device of claim 13, wherein the housing is configured to hold a plurality
of terminating ferrules.
19. The device of claim 13, wherein the base is removably secured to the first substrate.
20. The device of claim 13, wherein the first substrate is substantially parallel
to the second substrate.
21. The device of claim 13, wherein the first substrate is substantially orthogonal
to the second substrate.
22. A device for self-positioning a terminated conductor on a substrate, the
device comprising:
a housing for holding the terminated conductor, the housing slidably disposed
on the substrate by engagement of at least one channel on the housing and at least
one protrusion on the substrate such that the housing has a longitudinal range
of motion and a lateral range of motion with respect to the substrate in both mated
and unmated positions;
biasing means urging the housing along the longitudinal range of motion toward
a forward position;
wherein the engagement of the channel and protrusion direct the housing to a
predetermined lateral position as the housing moves toward the forward position; and
wherein the channel and protrusion are engaged in both the mated and unmated
positions of the housing.
23. The device of claim 22, wherein the predetermined lateral position is substantially
centered along the lateral range of motion.
24. The device of claim 22, wherein the lateral range of motion increases as
the housing moves away from the forward position.
25. The device of claim 22, wherein the conductor comprises an optical conductor.
26. The device of claim 22, wherein the conductor comprises an electrical conductor.
27. The device of claim 22, further comprising a base member interposed between
the housing and the substrate, wherein the base member is slidably engaged with
the housing.
28. The device of claim 27, wherein the base member is rigidly mounted on the substrate.
29. The device of claim 27, wherein the base member is movable relative to the substrate.
30. The device of claim 27, wherein the channel and protrusion are cooperatively
shaped to direct the housing to the predetermined lateral position as the housing
moves toward the forward position.
31. The device of claim 22, wherein the biasing means comprises a spring.
32. The device of claim 22, wherein the channel and protrusion are cooperatively
shaped to direct the housing to the predetermined lateral position as the housing
moves toward the forward position.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an interconnect alignment system for use with
optical and opto-electronic systems. More particularly, the present invention relates
to a device for providing alignment control during mating of an optical or opto-electronic
connector system.
Cabinets traditionally used for electronic devices are now being utilized
to accommodate optical and opto-electronic devices. In traditional cabinet designs,
the cabinet comprises a box having a plurality of internal slots (also known as
racks), generally parallel to each other. Components are mounted on planar substrates
(commonly referred to as circuit boards or daughter cards, or simply boards or
cards) which are designed to slide into the slots within the cabinet. As a card
is inserted into the slots within the cabinet, mechanical, electrical and/or optical
connections are formed with mating components in the cabinet.
Mating components in the cabinet are typically on a backplane in the cabinet.
A backplane derives its name from the back (distal) plane in a parallelepipedal
cabinet and generally is orthogonal to the plane of the inserted card. The term
backplane as used in connection with the present invention refers to an interconnection
plane where a multiplicity of interconnections may be made, such as with a common
bus or other external device. For explanation purposes, a backplane is described
as having a front or interior face and a back or exterior face.
An example of a backplane connectivity application is the interconnection of
telephone
switching equipment. In this application, cards having optical and electronic telecommunication
components are slid into cabinets. As a function of inserting and removing a card
from a rack coupled to the backplane, coupling and uncoupling of the electrical
and optical connections in the card must be completed in a blind mating manner.
To maintain appropriate transmission of light signals in an optical connection,
optical fiber ends should be carefully aligned along all three linear movement
axes (x, y, and z), as well as aligned angularly. Alignment challenges increase
and dimensional tolerances decrease as the number of optical fibers to be aligned
increases. Blind mating of a card-mounted component to a backplane connector has
been found to create special challenges with regards to alignment and mating force
issues along the axis of interconnection.
For the purposes of the present description, the axis of interconnection is called
the longitudinal or x-axis and is defined by the longitudinal alignment of the
optical fibers at the point of connection. Generally, in backplane applications,
the longitudinal axis is collinear with the axis of movement of the cards and the
axis of connection of the optical fibers in and out of the cabinets. The lateral
or y-axis is defined by the perpendicular to the x-axis and the planar surface
of the card. Finally, the transverse or z-axis is defined by the orthogonal to
the x-axis and the backplane surface. The angular alignment is defined as the angular
orientation of the card with respect to the x-axis.
Ideally, the motion of sliding the card into a receiving slot simultaneously
achieves optical and/or electrical interconnection between the card components
and the backplane. However, dimensional tolerances of the cards, the components
thereon and the slots themselves may result in excessive movement or "play" of
a card in a slot. Thus, when an operator inserts a card in a slot, it is often
difficult to maintain the leading card edge and components thereon in correct alignment
with the axes of the backplane.
To achieve a good interconnection, the card components should be properly aligned
along the longitudinal, lateral and transverse axes with the mating components
on the backplane as the card is inserted in the slot. Longitudinal misalignment
influences the "optical gap" (the distance along the longitudinal axis between
the optical fiber ends of interconnected optical components). An optical gap will
degrade the connection, resulting in the loss or degradation of the optical signals
and creates undesirable internal reflecting. On the other hand, excessive pressure
on the mating faces, such as that caused by "jamming in" a card, may result in
damage to the fragile optical fiber ends and mating components. Traditional optical
gap tolerances are in the order of less than one micron. Lateral and transverse
misalignment influence the ability to make an interconnection at all. If the card
is sufficiently misaligned along the lateral or transverse axis, stubbing of the
mating connector halves may occur and interconnection may be prevented completely.
FIG. 1A illustrates a linearly misaligned card
10 having a connector
12
mating to a backplane connector
14. In FIG. 1A, the card
10 is grossly
misaligned along the lateral (y) axis such that optical fibers
16 are not
properly aligned and interconnection is prevented.
Another consideration is angular misalignment of the card. FIG. 1B illustrates
angularly misaligned card
10. The card is otherwise correctly aligned along
the y and z-axes. At the point of contact between connectors
12 and
14,
the angular misalignment prevents correct optical gap spacing between optical fibers
16 and causes undue pressure on one end of the connector and the respective
optical fiber end faces.
An additional subject of concern is "card gap", especially when dealing with
backplane
connector systems. Card gap is defined as the space remaining between the rear
edge of a card and the interior or front face of the backplane. In general, designers
and users of backplane connection systems find it exceedingly difficult to control
the position of a card to a backplane within the precision range required for optical
interconnects. Card gap, otherwise defined as card insertion distance, is subject
to a multiplicity of variables. Among these variables are card length, component
position on the surface of the card, card latch tolerances, and component position
on the backplane.
Over-insertion of a card relative to the interior surface of a backplane
presents a separate set of conditions wherein the backplane connector's components
are subjected to excessive compressive stress when fixed in a mated condition.
In certain instances the compressive stress may be sufficient to cause physical
damage to the connector's components and the optical fibers contained therein.
The need remains for a connector system that prevents component damage due to
excessive operator force, compensates for linear card misalignment, yet provides
accurate control of optical gap distance and mating force.
SUMMARY OF THE INVENTION
The present invention provides an opto-electronic interconnect alignment system
that provides linear and angular alignment control. In one embodiment, the alignment
system of the present invention is useful for connecting at least one optical fiber
mounted near the edge of a planar substrate (such as a daughter card) to a backplane.
In one embodiment according to the invention, the connector alignment system
comprises
a base configured for mounting on a first substrate, and a housing movably engaged
with the base. The housing is configured to secure an optical or opto-electronic
termination, such as a terminating ferrule for an optical fiber. The housing has
a longitudinal range of motion and a lateral range of motion with respect to the
base. When the housing is in an unmated position, the lateral range of motion is
less than the lateral range of motion when the housing is in a mated position.
In another embodiment according to the invention, the housing has a transverse
range of motion, and the transverse range of motion is reduced when the housing
is in an unmated position. In another embodiment according to the invention, the
housing has an angular range of motion, and the angular range of motion is reduced
when the housing is in an unmated position. In other embodiments according to the
invention, different and various combinations of lateral, transverse and angular
ranges of motion are reduced when the housing is in an unmated position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a side elevation view of a linearly misaligned card and a backplane connector.
FIG. 1B is a side elevation view of an angularly misaligned card and a backplane connector.
FIG. 2 is an isometric cut-away view of a first embodiment of an interconnect
alignment system in accordance with the present invention in a mated card position.
FIG. 3 is an isometric view of the interconnect alignment system illustrated
in FIG. 2 in an unmated card position.
FIG. 4 is an exploded isometric view of the interconnect alignment system illustrated
in FIG. 2.
FIG. 5 is an isometric view of the housing member and base of the interconnect
alignment system illustrated in FIG. 2.
FIG. 6 is an exploded isometric view of another embodiment of an interconnect
alignment system according to the invention.
FIG. 7 is an assembled isometric view of the interconnect alignment system of
FIG. 6.
FIG. 8 is a bottom view of the interconnect alignment system of FIG. 7
DETAILED DESCRIPTION
In the following Detailed Description, reference is made to the accompanying
drawings
which form a part hereof, and in which is shown by way of illustration specific
embodiments in which the invention may be practiced. In this regard, directional
terminology, such as "top," "bottom," "front," "back," "leading," "trailing," etc.,
is used with reference to the orientation of the Figure(s) being described. Because
components of embodiments of the present invention can be positioned in a number
of different orientations, the directional terminology is used for purposes of
illustration and is in no way limiting. It is to be understood that other embodiments
may be utilized and structural or logical changes may be made without departing
from the scope of the present invention. The following detailed description, therefore,
is not to be taken in a limiting sense, and the scope of the present invention
is defined by the appended claims.
FIGS. 2 and 3 illustrate an embodiment of an interconnect alignment system
100 in accordance with the present invention. The interconnect alignment
system
100 controls alignment by providing a self-aligning interconnect
assembly
150 on a substrate. The self-aligning interconnect assembly is
configured for mating with a housing
120 on a second substrate. In one embodiment
according to the invention, the first substrate is a planar substrate, such as
a daughter board or circuit card
102 which may have optical, optoelectronic,
and electronic components thereon. The card
102 may be slideably inserted
in a slot
105 defined by card guides
106. In one embodiment according
to the invention, the second substrate is a backplane
104 having a through-opening
108 for receiving housing
120, a first interior surface
110
and a second, exterior surface
112.
Although the exemplary interconnect alignment system
100 is described
herein as providing alignment control between a circuit card or daughter board
and a backplane, such description is for illustrative purposes only. It should
be understood that the interconnect alignment system of the present invention is
useful in providing alignment control for other types and configurations of mating
connectors, and the invention is not to be limited to daughter board and backplane
type systems.
As illustrated, housing
120 is disposed within opening
108 of backplane
104. As best seen in the exploded view of FIG. 4, housing
120 defines
an array of four receiving cavities
132. Alternative embodiments may include
a single receiving cavity or any other necessary number of cavities to accommodate
various optical fiber cable connections. Each one of the cavities
132 includes
a front opening
134 and a rear opening
136. For the purpose of the
description of the present invention the terms rear, front, forward or backward
are merely illustrative to help describe the depicted embodiments with respect
to the figures. Optional folding front doors
138 are coupled to close the
front opening
134 and rear doors
140 are coupled to close rear openings
136. The front and rear doors
138 and
140 in the present embodiment
include flat spring metal members hingedly coupled to the front and rear openings
134 and
136. The doors
138 and
140 are designed to
fold down flat when a plug is inserted into the opening of the receiving cavity
132. In the present embodiment, the housing
120 comprises molded
plastic pieces of a dielectric material that exhibit sufficient structural strength
and dimensional stability to maintain control of the optical fiber's position.
Such materials include, but are not limited to, thermoplastic injection moldable
polymers that are filled or unfilled with reinforcement agents, and transfer moldable
polymers such as epoxy. The doors
138 and
140 are made of a conductive
metal material, such as tempered stainless steel, beryllium/copper alloys or other
materials, and are optionally coupled to provide a grounding electrical path. The
housing
120 may include mating features corresponding to common plugs or ferrules.
It should be understood that housing
120 need not be disposed on or through
a backplane as illustrated herein. In other embodiments, housing
120 may
be disposed on alternate substrates and take other configurations, so long as housing
120 is configured to mate with a card mounted connector assembly
150
as described below.
The front end of the backplane mounted housing
120 mates with card mounted
self-aligning connector assembly
150 when the card
102 is advanced
in the guide slots
105. The back end of the backplane mounted housing
120
mates with a plug assembly
142. The connector assembly
150 disposed
on card
102 includes a housing member
152 movably engaged with a
base member
156. Base member
156 is securely mounted on card
102.
In the illustrated embodiment, base member
156 is removably secured to card
102 using a combination of positioning pins
157 and screws
158.
Those skilled in the art will be readily aware of additional methods for attaching
base member
156 to card
102, in either a removable or permanent manner.
Alternative embodiments may include attachment means such as mechanical fasteners,
spring clips, adhesive or the like, or a combination thereof.
As best seen in FIG. 4, housing member
152 is movably engaged with base
member
156 via the engagement of channels
159 on housing member
152
with rails
160 on base member
156. Channels
159 and rails
160 are in generally parallel alignment with the longitudinal axis. Channels
159 and rails
160 are generally loosely fitted to each other and
are sized to permit housing member
152 to move or "float" relative to base
member
156 within a desired range of motion. The amount of float is preferably
sufficient to allow lateral, transverse, and angular movement of housing member
152 when mated with housing
120. In one embodiment according to the
invention, in the mated position, the range of motion of housing member
152
relative to base member
156 is in the range of approximately 0.030 to 0.050
inches in the lateral direction, and in the range of approximately 0.005-0.015
inches in the transverse direction. In the unmated position, the range of motion
of housing member
152 relative to base member
156 is in the range
of less than approximately 0.010 inches in the lateral direction, and in the range
of approximately 0.003-0.007 inches in the transverse direction. The illustrated
housing member
152 and base member
156 define an array of four channels
159 and rails
160. Alternative embodiments may include a single pair
of rails and channels, or any other number of rails and channels necessary to accommodate
various sizes of housing members.
As illustrated in FIG. 5, the longitudinal movement of housing member
152
is controlled by a spring assembly
182. In the illustrated embodiment, the
spring assembly
182 includes two springs
184 laterally spaced with
respect to each other and located generally at the lateral ends of the housing
member
152 and base member
156. Springs
184 are maintained
in a slightly compressed state between housing member
152 and base member
156, and are held in position by a mandrel
186 or other suitable
retention device. The term spring refers to a resilient or elastic member, such
as a coiled spring, a biasing clip, an elastic band, a compression foam, or other
similar devices known in the art. The spring assembly
182 serves to exert
a forward force along the longitudinal axis on the housing member
152, thus
urging housing member
152 to a forward position relative to base member
156. Housing member
152 reaches its extreme forward position when
housing member
152 is not engaged with housing
120 (i.e., housing
member
152 and housing
120 are in an unmated condition). As an additional
benefit, restorative forces are imparted to housing member
152 by springs
184 when lateral and transverse movement of housing member
152 occurs.
That is, springs
184 tend to resiliently resist lateral and transverse displacement,
thereby aiding in returning housing member
152 to a centered location.
Again referring to FIG. 5, housing member
152 and base member
156
are further provided with interacting alignment means
188 for directing
housing member
152 to predetermined lateral and/or transverse positions
relative to base
156 as the housing member
152 moves toward its forward
position under the biasing force provided by spring assembly
182. In the
embodiment illustrated in FIGS. 2-5, the alignment means include a tapered channel
or notch
190 on the housing member
152 configured to engage a mating
shoulder or protrusion
192 on the base member
156. The tapered notch
190 and shoulder
192 are cooperatively shaped to direct the housing
member
152 to a predetermined lateral and/or transverse position as the
housing member
152 moves toward its forward position. In the illustrated
embodiment, the housing member
152 is centered within its lateral range
of motion. As the tapered notch
190 engages shoulder
192, the lateral
range of motion gradually and smoothly decreases. Conversely, as housing member
152 moves away from the forward position (as when housing member
152
mates with housing
120), the lateral range of motion increases.
In alternate embodiments according to the invention, the cooperating notches
and
shoulders defining the alignment means may include notches and/or shoulders of
different shapes, or in different positions on housing member
152 and base
member
156. The position of the notches and shoulders could be reversed
(i.e., notches in base member
156 and shoulders on housing member
152).
The alignment means may direct housing member
152 to a position other than
a central position in a range of motion (e.g., to an extreme end of a range of motion).
In another embodiment according to the invention, as illustrated in FIGS. 6-8,
the alignment means are integrated into the channels
159 and rails
160
of housing member
152 and base member
156. Specifically, the dimensions
and shapes of channels
159 and rails
160 are varied and controlled
along the longitudinal axis such that the amount of "float" provided to housing
member
152 in the lateral and transverse directions varies in a desired
manner as housing member
152 moves in the longitudinal direction. The angular
range of motion is generally a function of the lateral and transverse ranges of
motion. By controlling the "float" of housing member
152 relative to base
156, the position of housing member
152 can also be controlled. In
the embodiment illustrated in FIGS. 6-8, the rails
160 are narrowed (i.e.,
moved closer together) near the front of base member
156. When housing member
152 is biased by the spring
184 to the forward (unmated) position,
housing member
152 becomes centered in the lateral direction as a result
of the reduced clearance created by the narrowing of the rails
160. A ramp
194 is provided to ease the transition of housing member
152 to its
centered position. The position of housing member
152 in the transverse
direction may be similarly controlled by increasing the thickness of rails
160
near the front of base member
156. When housing member
152 engages
housing
120, housing member
152 is pushed away from its constrained
forward position and the lateral, transverse and angular ranges of motion of housing
member
152 increase.
In an alternate embodiment according to the invention, the features of base member
156 are integrated directly into the substrate on which housing member
152
is disposed, and base member
156 is omitted as a separate and distinct component.
In the illustrated examples, base member
156 is rigidly secured to card
102. In other embodiments according to the invention, base member
156
is secured to card
102 such that base member
156 is able to move
or float relative to card
102. Base member
156 can be provided, for
example, with longitudinal, lateral, transverse, and angular ranges of motion relative
to card
102 by providing channel and rail engagement features between base
member
156 and card
102, similar to those described between housing
120 and base
156.
In each of the illustrated embodiments, the spring assembly
182 biases
the board housing member
152 towards the front or mating edge of the daughter
card
102, such that the housing member
152 is forced to move against
the resistance of springs
184 when the housing member
152 is moved
by an action opposite to that of the normal force of the springs
184, as
when housing member
152 mates with housing
120. The combination of
the forward bias of the springs
184 and the freedom of movement x
2
of the housing member
152 along the longitudinal axis allows compensation
for incorrect tolerances in the alignment of the card
102 with respect to
the housing
120 on the backplane
104. The combined force of the springs
184 is selected to be greater than the summation of all opposing spring
forces, such as those of the independent springs
178 of the individual mating
ferrule assemblies. Otherwise, the combined force of the springs
178 of
the ferrule assemblies would push the housing assembly backwards thus preventing
the desired coupling between the board housing assembly
150 and the backplane
housing
120. However, the independent ferrules still retain their range
of movement, thus assuring a tight fit on each individual optical cable connection.
Housing member
152 includes one or more hollow protrusions
154
shaped in size to correspond and fit into front openings
134 of a backplane
mounted housing
120. The protrusions
154 of housing member
152
in the present embodiment are hollow and rectangular shaped and are terminated
in a truncated pyramid shaped lead
162. The pyramid shaped lead
162
allow for compensation of small mating misalignments by directing the protrusions
154 into the receiving cavities
132 of the backplane mounted housing
120. Furthermore, the protrusions
154 are shaped to provide alignment
with respect to the inside walls of receiving cavities
132. Protrusions
154 also provide an automatic pressure for opening front doors
138
during mating. The inner walls of protrusion
154 define a stepped cavity
164 that provides guidance to a fiber optic ferrule
170 to be seated
inside of the stepped cavity
164. In the illustrated embodiments, the stepped
cavity
164 is shaped to receive an industry standard ferrule, such as the
MT-Style optical ferrules. Stepped cavity
164 is designed in such a manner
that it comprises a front and a rear rectangular opening
166 and
168,
respectively. The front opening
166 is sized to allow insertion of the ferrule
170 up to an internal flange
172.
As best seem in FIGS. 2 and 4, a typical MT-style connector includes a ferrule
170 mounted on a stalk of optical fibers
174, slidably connected
to a détente body portion
176. The ferrule
170 has a limited
range of motion x
1 along the longitudinal axis. The stalk of optical
fibers
174 is allowed to move with respect to the détente body portion
176. A spring element
178 located between the ferrule
170
and the détente body portion
176 forward biases the ferrule
170
towards a forward end of the range of motion.
In the illustrated embodiments, the housing member
152 of self-aligning
connector assembly
150 includes rear openings
166 designed to accept
the MT-style connector, including the détente body portion
176. The
détente body portion
176 is retained against flange
173 while
the ferrule
170 is allowed to extend inside of protrusion
154 up
to and through the front opening
168. The détente member
176
is designed in such a manner that as the member
176 is inserted into the
front of the stepped cavity
164, the spring
178 is compressed between
détente member
176 and the ferrule
170. The ferrule
170
is prevented from traveling freely through the front opening
168 by a flange
180 formed in the ferrule
170. The flange
180 is formed to
act as a travel stop for the ferrule
170 when flange
180 is engaged
with internal flange
172. The détente member
176 is provided
with a latch feature
196 that engages the side walls of rear opening
166
of the assembly
150. Latching features
196 may be provided on both
side surfaces of the housing assembly
150 and the détente member
176.
It may be desirable in some instances to remove détente member
176
from the housing assembly, and for these situations, a release feature is provided
in the side of the housing. This release feature
196 is preferably cantilevered
and allowed to pivot and thereby allowing the release feature to be sprung inwards
to release the corresponding latch feature
196.
The length of travel of the card
102 along slots
105 in card guides
106 is selected such that when in the coupled or mated position, the card
mounted self-aligning connector assembly
150 exerts spring force on the
backplane mounted housing
120. In a preferred embodiment, the width of the
card gap should be greater than 0, preferably greater than the combined travel
of the spring biased ferrules (typically 1 to 2 mm) relative to their respective housings.
The range of motion x
2 of the housing member
152 with respect
to the card
102 is sufficient to correct for tolerance errors in the range
of movement of the card
102 along the card guides
106, and to absorb
any excessive force imparted by the user when sliding the card before the card
is stopped by the backplane mounted housing
120 or by any stop features
that may be present in the card guides
106.
The present invention addresses issues of linear misalignment between components
on card
102 and mating components on backplane
104 by self-aligning
the housing member
152 in an unmated condition to a predetermined position
along its lateral and/or transverse ranges of motion. In one embodiment according
to the invention, when in an unmated position, housing member
152 is positioned
at the center of its range of lateral and/or transverse movement. Accordingly,
in the unmated position, housing member
152 is prevented from being at an
extreme location in its range of movement and is therefore prevented from gross
misalignment with housing
120, so that interconnection between housing member
152 and housing
120 can be assured. In the mated position, housing
member
152 is permitted its full range of lateral, transverse and angular
movement so that small ranges of misalignment may be accommodated. In addition,
in the mated position the housing member
152 is held tightly against the
housing
120 and is subject to a constant spring bias provided by spring
assembly
182. The advantage of providing the constant spring bias is to
ensure that intimate contact is maintained between the housing member
152
and
120 even in the event that the card
102 is subject to movement
during its operation.
Those skilled in the art will appreciate that the present invention may be
used when coupling a variety of optical devices and even non-optical devices that
require precise alignment. While the present invention has been described with
a reference to exemplary preferred embodiments, the invention may be embodied in
other specific forms without departing from the spirit of the invention. Accordingly,
it should be understood that the embodiments described and illustrated herein are
only exemplary and should not be considered as limiting the scope of the present
invention. Other variations and modifications may be made in accordance with the
spirit and scope of the present invention.
*
