Patent Description:
In the area of fiber optic connections, typical fiber optic systems usually have to establish a bi-directional pathway between a transmitter port on a first element and receiver port on a second element and vise versa. See for example schematic <FIG>. In order for such a bi-directional systems to function, it is a requirement that one end of a fiber be connected to the light emitting source of a first equipment, often a type of laser or light emitting diode, and the other end connected to a receiver port on a second equipment. For the second fiber in the bi-directional pathway, the other fiber needs to be connected to the light source on the second equipment and, at the other end, the receiver port of the first equipment.

Fiber optic connectors used for larger high-speed fiber optic systems often use multi-fiber cables supporting many bi-directional pathways. In one example the cables typically have <NUM> fibers in the cable, with the corresponding connectors for such cables housing multiple fiber optic members within the same connector body. Such a twelve fiber arrangement can support six of such bi-directional (duplex) pathways.

These connectors used for such high-speed fiber optic systems often employ what are termed multiple fiber optic members, called MPO (Multiple-Fiber Push-On/Pull-off) connectors and they typically support the twelve fiber (six duplex channel) arrangements within the same connector body.

Using <FIG> showing a single two way channel, there can be many segments of fibers between two components, each representing a fiber optic cable with a connector. In some cases, between segments, the fibers in the connector of a first segment pass directly across to the fibers of the second segment. However, in some cases, in order for the transmission signal to end up at the correct receiver port, at least one segment connection, the connectors must have the pin/fiber input/output on one side flipped so that the transmission signal exits on the other fiber in the channel.

This situation is referred to as connector "polarity" for each segment.

A fiber cable segment with two connectors at either end that result in the same polarity across the segment is referred to as method A and a fiber cable segment with two connectors at either end that result in a flip in the polarity across the segment is referred to as method B. In <FIG>, the first four segments are method A polarity, the fifth segment is method B polarity exhibiting a flip in the light pathways across the two fibers.

Depending on the various fiber optic equipment arrangements, in the prior art, to make the correct connections, the installer selects cable segments (i.e. pre-terminated lengths of cable) that have the correct polarity. The openings in the transceivers and adapters have a key opening and the corresponding MPO connectors on the cable have a key (see e.g. the trapezoid shaped "key" element. The MPO connectors will only fit into the slot with the key in the right space. For example, if an installer requires a polarity A connection, the two connectors on the end will have keys that force their insertion into the desired transceivers/adapters with the resulting connection being that shown in <FIG>. If an installer requires a polarity B connection ("flip"), the two connectors on the end will have keys that force their insertion into the desired transceivers/adapters with the resulting connection being that shown in <FIG>. As such bi-directional pathways connected with pre-terminated cables using MPO connectors, must still eventually result in one end of a fiber being connected to a source and the other end connected to a receiver and vice versa for each bi-directional pathway supported. As shown in <FIG>, the top <FIG> show Method A polarity where the blue fiber starts on position <NUM> on one connector on one side of the segment and is at the same location (position <NUM>) on the other connector on the other side of the segment. This method A polarity arrangement would be a straight forward connection that passes the same connection polarity to the next segment of the installation.

<FIG> show Method B polarity where the blue fiber starts on position <NUM> on one connector on one side of the segment and is at the opposite location (position <NUM>) on the other connector on the other side of the segment. With Method B polarity the remaining fibers in the connector on the second side of the segment are all also transposed in position vis-à-vis the first connector. The management of connections in such MPO connectors between sources and receivers and the polarity of such connections is described in the standard TIA-<NUM>-C. This method B polarity arrangement would be a connection that reverses the connection polarity going forward to the next segment of the installation.

As shown in <FIG>, in order for the light signal from one source to reach a receiver at the other end there typically must be an odd number of 'flips' in the cabling, where a `flip' indicates a method B polarity segment, so that the fiber in connector position <NUM> is connected to position <NUM> on the other side, the fiber in connector position <NUM> is connected to position <NUM> on the other side, etc..

These flips can be achieved via individual fiber assemblies and/or in the adapters that connect different fiber optic cabling segments together for example as shown in the basic design in <FIG> at segment <NUM>. However, since fiber optic networks are dynamic environments, connections are often added or subtracted and the number of required flips changes within the cabling arrangement between equipment. Ensuring that there are an odd number of flips then requires one or more of the fiber optic assemblies' polarity to be changed as the connections are added or subtracted. This requires the installers and/or end users to stock connection cables with MPO type connectors at either end of both type A and type B polarities and lengths for every possible network configuration, given that connection cables are pre-terminated with MPO type connectors of a fixed polarity. For example, the connection cables are typically pre-terminated with the MPO connectors and associated keying arrangement meaning that a particular patch cable is either a polarity A type cable or a polarity B type cable. One type of cord (e.g. type A) cannot be easily converted to a type B type cord.

When preparing an initial fiber optic arrangement (e.g. transceivers, adapter and patch cables) at a given location, the required polarity of fiber optic segments/cable connections is carefully considered during the design phase and is generally fixed upon completion because, as noted above, the patch cords come pre-terminated and the polarity of the connector(s) is set at manufacture. Returning to the concept of the relative arrangement of the keys on the connectors for fixing the polarity type of the patch cords, a patch cord having connectors for its end set at a first polarity (i.e. method A or method B) can only be used for example in <FIG> at certain segment locations. However, if for any reason the configuration changed, as will be explained in more detail below, the installer may require a new patch cord, possibly of a different length, and having its two connectors set at a different polarity. Consequently, end users must carry a large inventory of pre-terminated assemblies or order additional parts to allow for reconfigurations of the network topology.

As noted above, the polarity of an MPO (Multiple-Fiber Push-On/Pull-off) style connector, whether it be method A or method B is determined by the relationship between the fibers and a "key" on the connector body, which is why polarity is sometimes referred to as "keying.

Prior art <FIG> shows a perspective view of a standard prior art MPO connector (shown in <FIG> in front axial direction) that has a single fixed key on its body. A cable having such a MPO type connection pre-terminated thereon will thus have its polarity set at the time of manufacture. Some prior art arrangements have the ability to change the key/polarity of the connector by allowing for a changing of the key arrangement on the connector from one side to the other (i.e. if done on one side of a cable it would reverse the pre-terminated cable from type A polarity to type B polarity), these solutions require the disassembling and reassembling of connectors or the purchase of new connectors. This solution would allow an existing connection pre-terminated cable to be converted from one polarity to another to be re-used, for example when an existing fiber optic arrangement is re-arranged and requires a differ polarity connection. However, such connectors that require complicated means for changing the key/polarity setting on a connection, is time consuming and increases labor costs and/or material costs associated with these modifications.

The publication <CIT> describes a multi-fiber optic connector configured to include a switchable polarity key. The polarity key is removably secured in either a top or a bottom recess using a latching feature without having to disassemble the connector.

The present arrangement overcomes the drawbacks associated with the prior art and provides for a reversible polarity MPO type connector that can be used for pre-terminating a multi-fiber fiber optic cable. The reversible polarity MPO type connector has a removable key that can be easily moved from one side of the connector (e.g. top) to the other side (e.g. bottom) so that by changing one connector's polarity, the existing cable or patch cable can be re-used in a existing fiber optic arrangement undergoing modification (and possibly changing the number of "flips" between the transmitter and receiver) without worry of previous installation types or designs. The reversible polarity connector and removable (and re-insertable) key reduces installer's and customer's inventory, installation time, and ultimately lowers their cost as they can easily and quickly adjust the polarity of an existing cable.

Such a connector employs a removable key that allows a user to reverse the polarity of the connector without the need to open the connector housing. Additionally, the present connector can be employed in conjunction with a universal connector pin arrangement that also allows a user to remove and/or insert the key on the desired side of the MPO connector so that the cable can accommodate both polarities, again without the need for opening the connector body.

To this end a multi-fiber, fiber optic connector according to claim <NUM> is provided.

The present invention can be best understood through the following description and accompanying drawings, wherein:.

In one embodiment of the present arrangement as shown in <FIG> a connector <NUM> is provided at the end of a multi fiber cable <NUM>. Connector <NUM> has a housing and quick release <NUM>, strain relief/boot <NUM>, guide pins/guide pin openings <NUM> and a removable key <NUM> that fits into a corresponding channel <NUM> that extends back through housing <NUM> and in some instances extending further back through strain relief/boot <NUM>. The opposite side of connector <NUM> has a mirrored slot <NUM>' (see e.g. <FIG>) so that key <NUM> may be removed from one side of connector <NUM> to the other, or, in other words, moved from slot <NUM> and re-inserted on slot <NUM>' as discussed in more detail below. It is noted that connector <NUM> is shown with guide pin openings <NUM> (female) but all of the features of the present arrangement are equally applicable to connectors <NUM> with male pins extended/present as well.

As a basic explanation, the "key" (<NUM>) sets the order for which the fibers in connector <NUM> are presented to an additional opposing connector <NUM>. A receiver or transmitter has a key hole or opening that only allows a connector to fit in one way, with the key matching. It will not go in upside down (which would arrange the fibers left to right in the opposite direction) For this application when key <NUM> is on an 'active' side that refers to the side of the connector on which key <NUM> is inserted, either one of slot <NUM> or <NUM>'. If a key is said to be reversed then it means that key <NUM> is removed from slot <NUM>/<NUM>' on side of connector <NUM> and reinserted in slot <NUM>/<NUM>' on the opposite side of connector <NUM> (now reversing which side of <NUM> connector is "active" or can be inserted into a receiver/transmitter/adapter). If connectors of both regular and reversed active keys are compared, it would be found that the fibers in connector <NUM> are presented to an opposing connector in opposite order.

A typical cable <NUM> has two connectors <NUM>, one either side and the setting of keys <NUM> on the two connectors is what sets the polarity (arrangement of fibers from cable <NUM>) for connector <NUM> from the perspective of an opposing connector. Changing one key <NUM> from slot <NUM>/<NUM>' to the other slot <NUM>/<NUM>' in a connector <NUM> on one side of cable <NUM>, while not moving key <NUM> on connector <NUM> on the other side of cable <NUM> would change the polarity from/to method A to/from method B (see e.g. <FIG>).

Thus, as shown in <FIG>, key <NUM> positioned on the top of connector <NUM> is in a forward extended position within slot <NUM>. As shown in cut-away <FIG>, key <NUM> is positioned in slot <NUM> on the top of connector <NUM> in a forward position with slot <NUM>' on the bottom of connector <NUM> empty. Key <NUM> has a long extended tab <NUM> that passes under quick release <NUM> within slot <NUM> and either passes over strain relief/boot <NUM>, or through strain relief/boot <NUM> if slot <NUM> extends that far. In Picture 4A, extended tab <NUM> passes over strain relief/boot <NUM> but if desired, slot <NUM> can be extended through strain relief/boot <NUM> to allow extended tab <NUM> to rest therein, depending on the desired specifications of the customer.

Such an arrangement allows for key <NUM> to be moved from one side to the other of connector <NUM>, to alternately allow either side of connector <NUM> to be the "active" side. If a cable <NUM> has such a connectors <NUM> on one or both sides then if removable key <NUM> is moved from one side of the connector (e.g. top slot <NUM>) to the other side (e.g. bottom slot <NUM>') it will change the connection polarity of cable <NUM> from type A to type B.

Applicants note that there are two slots <NUM> and <NUM>' for key <NUM> on connector <NUM> so that a fiber optic segment/cable 12having two connectors <NUM> on either end may exhibit both A & B polarities options by moving key <NUM> between slots <NUM>/<NUM>' on one of either connector <NUM>. When a user wants a fiber optic segment to be polarity A, the user simply removes keys <NUM> from slot <NUM> on the top of one connectors <NUM> to slot <NUM>' on the bottom of connector <NUM> switching the order of fibers (i.e. left to right) at that connector <NUM> reversing the setting of cable <NUM> from/to method A/B polarity.

When key <NUM> is moved from slot <NUM> to slot <NUM>', nothing physically changes with the fibers in cable <NUM> in connector <NUM>. Rather, the only change with connector <NUM> is a flipping of the order the fibers within cable <NUM> on one side by flipping which side of connector <NUM> is "active" on that side of cable <NUM> (while keeping the other side's key setting the same. If both keys <NUM> were switched on both connectors on either side of cable <NUM> at the same time the polarity would remain the same).

It is noted that nothing is moving within housing <NUM>. Fiber position number is always referenced, by one of ordinary skill in the art, by holding the key up and looking from left to right. By having a key <NUM> that can be moved to opposing sides of connector <NUM> with the ability to "activate" one side or the other of connector <NUM> , this changes the definition of "up" for that connector. In other words, with a movable key <NUM> on connector <NUM> and the ability to easily change which slot <NUM>/<NUM>' key <NUM> is located in and thus what side of connector <NUM> is "active" (used to determine which way is "up"). This allows the user to reverse the order of the fibers presentation on a one connector <NUM> on one end of an assembly only, switching cable <NUM> from a Method A to a Method B or vice-versa.

Moreover, in the cut away example <FIG>, connector <NUM> shows key <NUM> in top slot <NUM> and bottom slot <NUM>' empty. As is evident from <FIG>, key <NUM> can be moved from slot <NUM> to <NUM>' (or vise versa) to change the orientation of one connector <NUM> (changing the polarity of cable <NUM>), without the need for opening any part of connector <NUM>, such as housing <NUM>, unlike the prior art configurations. Moreover, a removable key <NUM> and slot <NUM>/<NUM>' configuration is easy to manufacture and does not require significant modifications to the prior.

<FIG> shows two connectors <NUM> fitted into an adapter <NUM> which are used to connect two cables/patch cords <NUM> in the case where multiple cables are needed to span between the transmitter and the receiver (see e.g. <FIG> where adapters <NUM> would be located at the vertical segment dividers. Such a key arrangement, as shown in <FIG>, has key <NUM> in slot <NUM> on the top of connector <NUM> on cable <NUM> entering adapter <NUM> from the left and key <NUM> located in slot <NUM>' (not visible) on the bottom of connector <NUM> on cable <NUM> entering adapter <NUM> from the right. In addition to being able to change a key arrangement of a connector that is to be inserted into the receiver or transmitter it can also be changed at an adapter location illustrated here, by moving key <NUM> from slot <NUM>/<NUM>' to the other on one of these two connectors <NUM>. Key <NUM> can thus be moved from slot <NUM>/<NUM>' easily using extended tab <NUM> with no need for specialized tools and without disassembly of connector <NUM>, as keys <NUM> and extended tab <NUM> are within slot <NUM> are accessible through an opening in housing <NUM>.

It is noted that key <NUM> and extended tab <NUM> are identified with different element numbers but that is only for functionally explaining their use within the context of this invention. Removable key <NUM> is typically made from a semi-rigid or rigid polymer, usually the same material used for housing/quick release <NUM>. Such material is typically selected to be able to withstand the stresses, strain and wear associated with about <NUM> or more mating cycles. The width, dimensions, and overall size of removable key <NUM> is generally specified in industry standards such as IEC <NUM>-<NUM> and TIA/EIA <NUM> and other standards pertinent to MPO type connectors.

One exemplary arrangement for demonstrating the usefulness of connector is shown in <FIG>. In <FIG>, a first equipment #<NUM> is shown connected to a second equipment #<NUM> using five spans of fiber with MPO type connectors on such spans at four locations (#<NUM> - #<NUM>). That is, at each location #<NUM> - #<NUM>, there is an adapter <NUM> and two opposing MPO connectors, one for each segment on either side of the adapter. The cables <NUM> between equipment <NUM> and adapter <NUM> and between adapters <NUM>-<NUM> are each polarity A type cables that maintain the same polarity from the prior segment (Method A polarity). In this arrangement and example, the span/cable <NUM> between connector adapter <NUM> and equipment <NUM> requires a polarity reverse so cable <NUM> therebetween is a Method B polarity cable <NUM> reversing the fiber order left to right from the prior segment (Method A polarity) from one side of cable <NUM> to the other.

Turning now to <FIG>, assuming that owing to some required connection change, equipment #<NUM> now needs <NUM> be replaced by equipment #<NUM>, that requires the last cable <NUM> to be polarity A (i.e. same all the way across) As a result the prior cable <NUM> in the last segment needs to have the polarity changed. Under the prior art, with fixed key pre-terminated cables the installer would need to either change a connector or get a new cable for the segment. Using the present arrangement key <NUM> on one connector <NUM> in cable <NUM> between adapter <NUM> and equipment <NUM> can be moved as needed between slot <NUM>/<NUM>' and the polarity of that cable <NUM> is now correct for the updated arrangement. The existing pre-terminated cable <NUM> can be used with only minimal effort to move key <NUM> between slots <NUM>/<NUM>'. Even if the installer was using prior art connectors that could change polarity, they would be of the type that required the installer to open the housing of the connector and change the polarity and reassemble the connector, possibly damaging/diminishing that connector and the fiber connections therein.

Claim 1:
A multi-fiber, fiber optic connector (<NUM>), said connector comprising:
a housing (<NUM>) having a first end for receiving a multi-fiber fiber optic cable (<NUM>) and a second end having openings for said fibers from said cable;
first and second key slots (<NUM>, <NUM>') configured to accept a removable key (<NUM>) for setting the polarity of said fibers within said connector (<NUM>), with said first and second key slots (<NUM>, <NUM>') located on opposing sides of said connector, said removable key having an extended tab portion (<NUM>) for moving the removable key (<NUM>) from said first and second key slots (<NUM>, <NUM>');
either one of guide pins or guide pin receiving holes (<NUM>) for guiding the connection with a second connector, and a strain relief (<NUM>),
wherein said removable key (<NUM>) is movable between said first and second key slots, said key slot (<NUM>, <NUM>') with said removable key corresponding to a first active slot and said key slot without said removable key corresponding to a non-active slot, such that when said removable key is in said first key slot, resulting in said first key slot being active, said fibers are presented within said connector in a first polarity and when said removable key is moved from said first key slot to said second key slot, activating said second key slot and deactivating said first key slot, said fibers are presented within said connector in a second polarity, reversed from said first polarity,
wherein the connector is configured to have said extended tab portion (<NUM>) to pass under said housing (<NUM>) within said active key slot and to pass over or through said strain relief (<NUM>).