 |
Description  |
|
|
TECHNICAL FIELD
The invention relates to fiber optic connectors and particularly to such
connectors as used in information handling systems (computers) and the
like which utilize printed circuit cards and/or boards.
BACKGROUND
Manufacturers and those who utilize information handling systems have
become extremely interested in the use of optical fibers as a means for
transmitting information. Advantages of optical fibers over other kinds of
transmission media are well known. For example, such systems are resistant
to electromagnetic interference which occasionally plagues systems using
electrical cables. Additionally, optical systems are considered more
secure than electrical systems since it is substantially more difficult
for unauthorized personnel to tap or access an optical fiber without being
detected.
As is also known, optical fibers transmit information using single or
multiple strands of fibers each having an inner circular glass core coated
with a circumferential cladding having a different index of refraction.
Light is transmitted along the core and reflected internally of the
cladding. Transmission lines as used in information handling systems known
today are formed of either a single fiber or a plurality (bundle) of such
fibers encased within a protective sheath. As also known, such fibers are
coupled to various fiber optic connector assemblies and utilized within
computers in selected manners.
One such example is shown in U.S. Pat. No. 4,678,264 (Bowen et al). Such
connections are typically of the single or duplex variety, the latter
involving a pair of optical fiber cables terminating within a single
connector member which is designed for being inserted within a respective
housing located on a designated component (e.g., a printed circuit card)
which forms part of the computer. In the case of a single cable, this is
also located within a connector member designed for insertion within a
respective housing. Such housings may be positioned on or relative to the
circuit card and are particularly designed to accommodate the fiber optic
connector therein such that appropriate optical connections can be
accomplished between the optical fibers and associated elements (e.g.,
transmitters and receivers) employed in the system when the connector is
so positioned. In those situations wherein transmitter and receiver
elements are used in a paired, adjacent orientation and coupled to the
circuitry of the circuit card or like member, a duplex form of connector
is preferably used. Further, it is also known in such computer systems to
utilize a plurality of such cards and electrically connect these to a
common backplane circuit board member or the like, said board member also
forming part of the overall system. The various cards, board, connectors,
wiring and several other elements are located within what is often
referred to as a cage assembly, which assembly may form one of several
such assemblies within the overall system. Still further, such computer
systems may in turn include their own power supply or the like, which in
turn may be connected to a local power source.
Many in the computer industry have expressed the desire to make electrical
connections between the circuit card and board components within the
system without shutting down the system. This is desired to permit card
replacement, repair and upgrading without interruption to the services
being provided by the computer. This feature is particularly desired by
those among the telephony and high end computer users and designers.
Early attempts at such "power on" connections were achieved by simply
plugging in the card while the computer was in operation. The unfortunate
results of such an operation included the formation of arcs where such
connections were made or broken. Additionally, errors in software
operation were detected during such connections, subsequently attributed
to the aforementioned arcing. More drastically, on some occasions the
connection did fail, said failure also deemed the result of the arcing.
Arcing of this type particularly occurs when a significant potential
difference exists between the board and card members. Excessively high
current flows as the result of the system's power supply charging the
capacitance of the card as rapidly as possible. By way of example, the
portion of the connector within the computer into which the card is to be
inserted may be at a voltage of about 25 volts while the card is at a
voltage of zero. Arc generation resulting from such a differential may in
turn create "noise" in the form of electromagnetic waves which propagate
within the computer, affecting other components (occasionally in an
adverse manner). For example, such components may pick up this noise as a
standard internal signal and react accordingly. Significant errors can
thus be created in both system and software operation as a result of such
arcing.
To overcome the above highly undesirable results, while still providing
desired optical connections between selected optical fiber elements and
respective components which form part of a circuit card member, the
present invention provides a fiber optic connector assembly capable of
being positioned on such a circuit card and adapted for not only receiving
a fiber optic connector but also uniquely providing a means whereby
electrical connections can be made to the circuit card in the same
vicinity of the card as the connector assembly's housing such that
charging of the card and its electrical components (e.g., to the potential
of the board to which this and other cards may be electrically coupled)
can occur, thereby preventing arcing or the like from occurring during
such coupling or uncoupling. As will be defined further herein, such
charging of the card occurs with the card separated from the mother board
member such that the card's electrical potential can be raised to that of
the board whereupon card coupling can occur. The charging unit can then be
facilely removed from the card and the desired fiber optic connector
positioned within the assembly.
It is believed that such a connector assembly would constitute a
significant advancement in the art.
DISCLOSURE OF THE INVENTION
It is a primary object of the invention to enhance the art of fiber optic
connectors and particularly those used in information handling systems or
the like which utilize circuit card and board assemblies.
It is another object of the invention to provide an improved fiber optic
connector assembly which enables both optical and electrical connections
to occur therein.
It is yet another object of the invention to provide such an assembly which
operates in a relatively simple manner and which can be produced
relatively inexpensively.
These and other objects, advantages and features are achieved in accordance
with one aspect of the invention by an improved fiber optic connector
assembly for use as part of a circuit card assembly to provide optical
connections to selected circuitry which forms part of the circuit card.
The connector assembly includes a housing positioned on the card and
designed for having the fiber optic connector positioned therein such that
these connections can occur. Additionally, means is also provided in the
invention whereby electrical connections can be made to the card's
circuitry in the same area of the card occupied by the housing such that
electrical charging of the card can occur in this area.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a plurality of improved circuit card
assemblies in accordance with a preferred embodiment of the invention,
each of said assemblies shown as being positioned (in a side-by-side
relationship) on a circuit card member designed for being electrically
coupled to a mother circuit board;
FIG. 2 is an enlarged view, partially in section, illustrating one of the
circuit card assemblies of the invention wherein an electrical connector
is shown as being positioned within the assembly's housing atop the
circuit card;
FIG. 3 is a front, partial perspective view of one of the assemblies of the
invention, more clearly illustrating one example of how various electrical
connections may be made to preselected circuit layers located within the
circuit card by the circuit tabs of the invention;
FIGS. 4 and 4A represent perspective views of two different embodiments of
electrical connectors which can be used in the invention to accomplish
electrical charging of the invention's circuit card, the embodiment in 4A
being one wherein different length contacts are used to provide sequential
charging of the card; and
FIG. 5 is an exploded perspective view of an improved circuit card assembly
of the invention, illustrating one embodiment of a charging assembly
(including electrical connector and handle) capable of being used to
charge the assembly's card.
BEST MODE FOR CARRYING OUT THE INVENTION
For a better understanding of the present invention, together with other
and further objects, advantages and capabilities thereof, reference is
made to the following disclosure and the appended claims in connection
with the above-described drawings. drawings.
With particular attention to FIG. 1, there is shown an improved circuit
card assembly 10 in accordance with a preferred embodiment of the
invention. Circuit card assembly 10 includes a circuit card 11 and at
least one fiber optic connector assembly 13 which is located on card 11
and designed for being optically connected to corresponding circuitry of
the card. In the invention depicted in FIG. 1, four assemblies 13 are
shown and positioned on the singular card 11 in a side-by-side
relationship. Each assembly 13 is fixably secured to the card and includes
a housing 15 as part thereof and designed for receiving therein a fiber
optic cable connector 17 (three of the four being shown in FIG. 1). Each
fiber optic cable connector 17, in one embodiment of the invention, is of
the duplex connector variety (containing two optical fiber elements
therein). In the particular embodiment of the invention depicted herein,
each of the fiber optic connector assemblies 13 also includes both
transmitting and receiving elements located therein (e.g., within the
structure 21 adjacent housing 15). Such components (transmitters,
receivers) are known in the art and typically include a pin diode or
similar receiver for receiving the optical signal through one of the
respective optical fibers and a transmitting component (e.g., laser or
LED) designed for transmitting optical signals to the other optical fiber
within the inserted duplex connector. Elements of this type are known in
the art, including the defined duplex connectors, and further description
is not believed necessary.
As understood herein, each of the fiber optic connector assemblies of the
invention is designed for being fixedly positioned on an outer edge
portion of card 11 such that access thereto (for insertion of the
respective fiber optic cable connectors and, as defined below, the
charging electrical connector of the invention) can be readily achieved in
most cage assembly configurations. This represents a highly advantageous
feature of the invention in that both side and top access is afforded,
given the configurations for most of these cage assemblies currently known
in the art. As such, each fiber optic connector assembly 13 is located
adjacent a predetermined area 31 on each card, said area 31 in the
preferred embodiment of the invention extending substantially to the
outermost edge of the card and projecting an established distance toward
the center of card 11. As shown, the housing 15 for each assembly is
located immediately adjacent (relative to) the respective one of each
areas and the remaining structure 21 of each such assembly extends
inwardly toward the center of card 11. The housing 15 (and structure 21 as
well) of each assembly 13 is thus mounted substantially flush to the
external surface of the card 11.
Each of the transmitting and receiving elements (not shown) in structure 21
is electrically coupled to corresponding circuitry within card 11
utilizing known means. For example, each of these elements may include a
pinned portion (e.g., three copper wires, bent at predetermined angles)
which is inserted within the card and thereby electrically connected to
respective circuit layers within the card (such cards typically of
multilayered configuration having more than one conductive (e.g., signal,
power) layers therein separated by appropriate dielectric material).
Alternatively, it is also possible in this invention to utilize an
additional substrate member (e.g., ceramic) having circuitry thereon and
electrically connecting such elements thereto. This added substrate's
circuitry may in turn be electrically connected (e.g., using metallic
pins) to the card's circuitry in a predetermined fashion. Such an
additional substrate and other essential elements used in conjunction
therewith can also be positioned within the adjacent structure 21 which
forms part of each assembly 13. To provide heat sinking, each of these
structures may also include a suitable heat sink or the like as part
thereof and may also be of a suitable heat conducting, metallic material
(e.g., aluminum) as is known in the art. Further description of these
structures is thus believed not necessary.
Connector 25 may comprise what is referred to in the art as a zero
insertion force connector having an elongated slot therein and a plurality
of cam-actuated spring contacts (not shown) located within the connector's
housing and designed for engaging respective circuitry located on card 11
when the card is inserted within the housings' slot and the contacts are
actuated (e.g., by a handle-actuated cam). Such connectors are known in
the art and further description is not believed necessary.
As stated above, it is highly desirous in the computer industry to provide
a means whereby circuit cards can be plugged and unplugged from the
respective mother board while the computer remains in operation. Thus, it
is not necessary to shut down the computer and interrupt the services it
provides during such removal (e.g., for purposes of replacement or
modification or repair). As also stated, however, accomplishing such a
feat has in the past resulted in undesirable occurrences such as
connection failure, software inoperation, and failure of some of the other
components within the final cage assembly (e.g., those also constituting
part of the circuit board's structure). These undesirable results, as
mentioned, have been determined to be the result of arcing which has
occurred at the point of coupling and uncoupling of the circuit card with
the mother board.
In order to substantially prevent the above, it is the purpose of this
invention to provide means to raise (charge) the voltage level of the
circuit card assembly (card and electrical components thereon) to the
approximate voltage level of the corresponding mother board prior to
insertion of the card within the connector 25 (and thus coupling thereof
to the circuitry in board 23). As defined herein, card 11 is to be charged
to this higher level prior to insertion and connection of the card within
board 23 as defined above and is to be maintained at this charged level
during such insertion and connection. As defined herein, the invention has
proven capable of providing this highly advantageous feature while
substantially eliminating the formation of such arcs or the like and the
highly undesirable results thereof.
In accordance with the teachings of the invention, at least one (and
preferably all) of the fiber optic assemblies 13 used herein includes
therein means for providing for electrical connection to the circuit card
to achieve this electrical charging thereof prior to positioning of the
card and coupling thereof to the active mother board component.
Understandably, after this coupling has occurred, the charging means as
defined herein is designed for being removed from the card and, uniquely,
the respective fiber optic cable connector 17 may then be located within
the same housing from which this connector (41) was removed. In accordance
with the preferred teachings of the invention, this means for charging
card 11 is accomplished in the same predetermined area of card 11 as
occupied by housing 15 of each assembly 13. Thus, such charging occurs at
the outermost edge portions of each card to thereby assure the ready
access to the card when the card is located within the designated cage
assembly. Insertion and removal of each card is thus facilitated by this
arrangement, when using the preferred charging means defined herein. As is
further understood, this orientation also facilitates alignment of the
circuit card prior to such insertion within the respective connector 25 or
similar member used to provide coupling to board 23.
To achieve such charging, an electrical connector 41 having substantially
similar outer dimensions to that of the respective duplex connectors 17 is
utilized and positioned within a respective one of the housings 15 of the
fiber optic connector assembly 13. Because four such assemblies are
depicted in FIG. 1, it is possible to utilize a corresponding similar
number of such charging electrical connectors. It is to be understood,
however, that effective charging of card 11 may be possible using but a
singular electrical connector 41. It is also understood that once
electrical connector 41 is removed from the respective housing 15, one of
the duplex connectors 17 is then inserted within this same housing to
complete the desired optical connections. Such connections are not
achieved, however, until the circuit card is firmly positioned and
electrically connected to board 23. Thus, it is understood that in FIG. 1,
card 11 will not be connected to board 23 until the electrical connector
41 has been positioned within respective fiber optic connector assembly 13
and sufficient charging has occurred. Should only one connector 41 be
utilized with the other (e.g., three) duplex connectors 17, is possible to
insert each of these duplex connectors within their own respective fiber
optic connector assembly prior to such card positioning. It would then be
only necessary to remove a singular connector 41 and insert a duplex
connector 17.
In the enlarged view depicted in FIG. 2, the positioning relationship of
electrical connector 41 within housing 15 of assembly 13 is better
illustrated. This charging connector 41 is inserted within housing 15 and
includes a plurality of electrical contacts 43 (only one shown in FIG. 2),
each being designed for slidably engaging a respective one of a plurality
of conductive circuit tabs 45 located on the upper surface 47 of card 11
and electrically coupled to respective circuit layers within the
multilayered card. Such connections, in one example of the invention, are
schematically represented in FIG. 3. In the embodiment shown in FIG. 3,
eight circuit tabs 45 are utilized. It is to be understood, however, that
the invention is not to be limited to this number of such tabs and/or
electrical contacts, as several different numbers may be employed.
Each tab 45 is a metallic member (e.g., copper) of a elongated
configuration and is spacedly located on surface 47 in a substantially
parallel relationship to the remaining tabs 45. As stated, the invention
is not to be limited to the use of eight such circuit tabs. It is
understood that, for purposes of the invention, a minimum of two such tabs
is required, one being electrically connected to the card's ground plane
(e.g., 51) and to the other one of the power planes (e.g., 53) which form
part of a multilayered card. In one example of the invention, a total of
five conductive layers (51, 53, 55, 57, 59) were utilized and connections
made to three of these by the illustrated six tabs in the manner shown in
FIG. 3. Duplication is thus provided, although not necessary in the
broader aspects of the invention. The sectioned, five conductive layers
depicted in FIG. 2 (and shown in an expanded view in FIG. 3) represent
conductive layers which, as stated, may include one ground plane (51) and
at least one power plane (53). In the embodiment depicted in FIG. 2, the
upper layer 55 preferably comprises a signal plane as may the lowermost
layer 57. Further, the layer 59 preferably constitutes a power plane but
at a voltage slightly less than that of power plane 53. The respective
layers of dielectric (not shown in section in FIG. 2) which are necessary
in a card component such as circuit card 11 to electrically isolate the
respective conductive layers are understood to occupy the relative
spacings between each conductive layer and lie contiguous thereto.
Additionally, dielectric (48) is also preferably utilized on the uppermost
and lowermost surfaces of the card, thus covering the outer surfaces of
signal planes 55 and 57. As noted in FIG. 2, a portion of the upper
dielectric 48 is located under the individual circuit tabs 45 to
electrically isolate these from upper conductive layer 55 (except for the
tab (or tabs) which will be directly connected to layer 55; here, a
portion of dielectric 48 may be removed or connection made therethrough).
One example of a suitable dielectric material for use herein is epoxy
resin, such a material being known in the art. As stated, electrical
connection is necessary between two tabs 45 and a corresponding power
plane and ground plane layer. In the side sectional view of FIG. 2, the
tab 45 as shown is electrically connected firmly to the power plane 59 and
is insulated from the remaining conductive layers within card 11 (by
dielectric 50 located in the hole extending through the card). In the
aforementioned example wherein five conductive layers were used, the power
plane 53 was established at a voltage of about five volts while the lower
power plane 59 was established with a voltage of about 3.5 volts. Because
charging only occurs through the power and ground planes, connection
between tabs 45 and the respective signal planes 47 and 57 is not
necessary.
Each of the spring contacts 43 used within connector 41 is preferably
metallic (e.g., phosphor bronze or copper) and possesses a curvilinear
shape (FIG. 2) or is of the angled configuration such as depicted in FIGS.
4 and 4A.
As shown in FIGS. 4 and 4A, the plurality of spring contacts 43 can better
be seen with respect to their orientation within the insulative housing
member 59 designed to contain these elements. Each spring 49 is in turn
electrically coupled to a respective conductive wire 61 which in turn is
coupled to the respective power source (not shown) which provides the
appropriate power to effect charging of card 11 and its components.
Although not meant to limit the invention, each spring contact 43 includes
a projecting leg section 63 which extends through the insulative member 59
and projects externally thereof. Accordingly, each wire 61 is electrically
connected (e.g., soldered) to the projecting spring, this wiring (and
springs) being surrounded by appropriate insulation (not shown). Spring
contacts are preferably utilized to assure an effective wiping type of
engagement between the surfaces of each tab 45 and respective contact.
Such wiping serves to remove contaminants and other undesirable materials
which may adversely affect the sound connection at this point.
As clearly shown in FIGS. 1-3, the aforementioned electrical connections
between contacts 43 and respective circuit tabs 45 is accomplished through
an opening 65 located within housing 15 adjacent card area 31. Housing 15
is preferably thermoplastic or the like material and an opening may be
best easily provided therein in the form of an elongated slot. With the
circuit tabs mounted on card 11 as shown and housing 15 in turn located
flush to the upper surface 47 of the card, it is seen that each of the
circuit tabs is located substantially within the housings' opening and
substantially encased by the housing (except for the forward opening into
which connector 41 is inserted).
In a preferred embodiment of the invention, electrical connection between
the tab 45 and respective conductive layer is accomplished by using plated
thru hole technology known in the art. That is, a hole is drilled through
the circuit board to the appropriate depth and insulation (e.g.,
dielectric 50) is provided within this hole (which is plated with a
conductive material such as copper) between this plated structure and the
remaining conductive layers to which contact is not desired. A pin 52 or
similar member secured to or forming part of the respective tab 45 and
projecting therefrom may be inserted within the plated thru hole to
provide the appropriate connection. An example of such an arrangement is
depicted in FIG. 2.
In the embodiment of FIG. 4A, the spring contacts 43 are shown as being of
different lengths (in sets of two) such that the invention using this
embodiment of the electrical connector will provide for sequential
engagement with tabs 45. That is, the longest (or forwardmost) contact
("F") in each grouping will provide initial engagement with a respective
circuit tab 45 (all of which are of equal length) while the next longest
spring contact ("F1") will become subsequently engaged during forward
insertion (direction "FF") in FIG. 4A within the respective housing 15
(not shown in FIG. 4A). Subsequently, the next longest spring contact will
make engagement with its own circuit tab, followed by engagement with the
next longest (and shortest) spring contact. This staggered contact
arrangement assures sequential voltage application to the respective
circuit card prior to its insertion and coupling within connector 25 to
thus further assure that excessive voltage is not present across the card
and its components during initial charging. It is to be understood,
however, that if the components used as part of the card are capable of
withstanding such initial charging, such a staggered orientation of
different length spring contacts may not be necessary. The arrangement
depicted in FIG. 4A is preferred, however, to further prevent the
opportunity for this undesirable occurrence.
In FIG. 5, there is shown an electrical connector 41' in accordance with an
alternative embodiment of the invention. As shown in FIG. 5, connector 41'
includes the aforementioned insulative block or similar member 59 having
therein the desired plurality of spring contacts (not shown). In the
embodiment of FIG. 5, two such electrical connector insulative blocks 59
or the like are utilized to thus provide dual charging capabilities to
card 11. It is understood tha | | |
