Abstract:
An optical transceiver providing a carrier; a cover couplable to a portion of the carrier to define a transceiver enclosure; and, an electro-optical assembly supported in the enclosure is provided. A coupling mechanism and cooperating structure are particularly adapted to define pivoting motion of the cover relative to the carrier, whereby interference of the cover and the electro-optical assembly is avoided. Methods of assembling the transceiver components are present.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to a laser-based data communication interconnect apparatus for effecting optical data transfer and, more particularly, to a compact optical transceiver apparatus having an improved housing with an improved coupling mechanism and method of assembly. 
   Optical transceiver modules are known in the data transmission field for effecting bidirectional data transmission, whereby electrical signals are converted to optical signals and vice versa. In operation, a transmitter unit of the optical transceiver module functions to convert incoming electrical signals to corresponding optical signals. Conversely, incoming optical signals are converted by the optical transceiver module&#39;s receiving unit into corresponding electrical data signals. These units are typically mounted on a circuit host card that is normally associated with a host computer, input/output device, switch, or other peripheral device. 
   In general, transceiver module compactness for achieving space saving concerns is important particularly in situations wherein many optical transceiver modules are closely mounted on a data system for increasing port density. Such concerns become even more pronounced when it is desired to satisfy established as well as emerging standards relating to size and form factor. However, because these optical transceiver modules are relatively expensive to manufacture and relatively fragile in construction, it is important to avoid damaging them during the assembly process. Typically, during optical transceiver module assembly a heat sink cover is manually placed over and on a carrier base that supports a printed circuit board having expensive and compactly arranged electro-optical components of the optical transceiver module mounted thereon. Unless significant care is exercised in the assembly process due to the tight tolerances between such components as required by compactness constraints potential damage may occur. Further, there is a concern for being able to easily reopen and close the optical transceiver module for inspection and/or repair of the internal circuit board and the components carried thereon without damaging them. Moreover, there is a desire to not only make such transceivers easy to assemble, but to do so in a manner which does not compromise the integrity of effective electromagnetic interference (EMI) shielding. 
   Without the ability to effectively and efficiently assemble such optical transceiver modules, given the compactness constraints for meeting existing and emerging standards, by avoiding damage to their components, the potential value of providing low-cost and reliable optical transceivers is diminished. 
   Given the above, it will be appreciated, that there is a desire to provide for: optical transceiver modules that have compact constructions satisfying existing and emerging standards regarding size and form factor; optical transceiver modules wherein the assembly process can be carried out in a manner that reduces the likelihood of components being damaged; optical transceiver modules that are less costly to assemble; optical transceiver modules having the ability to protect interior components of the transceiver during repair and/or reconstruction; and, optical transceiver modules that achieve the foregoing without compromising desired EMI shielding. 
   SUMMARY OF THE INVENTION 
   It is, therefore, a principal aspect of the present invention to make provision for a compact optical transceiver module that has a relatively simple construction requiring few components for effecting ease of assembly and disassembly of the optical transceiver module. 
   It is, therefore, another principal aspect of the present invention to make provision for a compact optical transceiver module of the above type that minimizes the potential for damage to costly components of the optical transceiver module during assembly and/or disassembly thereof. 
   It is yet another aspect of the present invention to make provision for a compact optical transceiver module that has a relatively simple construction that facilitates safe and easy enclosing of expensive and fragile components requiring relatively compact space considerations during the assembly process. 
   It is, therefore, another principal aspect of the present invention to make provision for a compact optical transceiver module that is economical to manufacture and assemble. 
   It is, therefore, another principal aspect of the present invention to make provision for a compact optical transceiver module of the foregoing types that allow the optical transceiver module to meet existing and emerging standards as to size and form factor. 
   In regard to achieving the foregoing aspects, the present invention makes provisions for an optical transceiver that comprises: a carrier; a cover couplable to cooperating structure of a distal portion of the carrier to define a transceiver enclosure; an electro-optical assembly supported in the enclosure; and, a coupling mechanism coupled to the cooperating structure for allowing pivoting motion of the cover relative closed and opened conditions relative to the enclosure about a pivoting axis offset from the transceiver. 
   In an illustrated embodiment the coupling mechanism allows the cover to move to the closed condition without interference with upstanding components of the electro-optical assembly. 
   Further consistent with achieving the foregoing aspects and improving on the prior art the present invention makes provisions for the coupling mechanism allowing the cover to move to the closed condition without applying loading to upstanding components of the electro-optical assembly which might be sufficient to damage such components. 
   Further consistent with achieving the foregoing aspects, the present invention makes provisions for a method of assembling components of an optical transceiver. The method comprises the steps of: providing a carrier; providing a cover joinable together with the carrier to define an enclosure therebetween; providing an electro-optical subassembly within the enclosure and supported by the carrier, providing a coupling mechanism on one of the carrier or the cover; providing a cooperating structure on the other of the carrier and cover; and, assembling the cover to the carrier so that when the coupling mechanism is joined to the cooperating structure, the cover pivots in a controlled path between opened and closed conditions about an axis remote from the transceiver, whereby interference of the cover or the electro-optical assembly is substantially minimized or eliminated. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, reference is now made to the following detailed description of a preferred embodiment of the present invention illustrated in the accompanying drawings in which: 
       FIG. 1  is a schematic plan view of an optical transceiver of the present invention mounted on a host circuit card of a data transfer system of the present invention; 
       FIG. 2  is a schematic view of the optical transceiver in an assembled condition; 
       FIG. 3  is a schematic view similar to  FIG. 2 , but illustrating the transceiver partially in a disengaged/engaged position; 
       FIG. 4  is a schematic view similar to  FIG. 3 , but illustrating the heat sink cover removed from the carrier; and, 
       FIG. 5  is an enlarged and fragmented perspective view of the coupling mechanism in the position depicted in  FIG. 3 . 
   

   DETAILED DESCRIPTION 
     FIGS. 1–5  illustrate one preferred embodiment of an optical transceiver module  10  made according to the principles of the present invention and illustrated as being mounted in a host data transfer system  12 . 
   With reference to  FIG. 1 , a first or proximal end portion  14  of the optical transceiver module  10  is to be coupled directly to a card edge connector  16  that is covered in a metal shroud  18  and is otherwise connected to a network adapter card  20  housed within the confined space  22  formed by the host data transfer system  12 . The host data transfer system  12  can be a mid-range computer system commercially available from International Business Machines Corporation, Armonk, N.Y. Other types of data transfer or communication systems are contemplated for use with the optical transceiver module  10  of the present invention, such as input/output devices or other peripheral devices. The optical transceiver module  10  is otherwise slideably received within one of a plurality of elongated slots  24  formed in the network adapter card  20  in a manner to be described. A suitable connector end portion  26  at the distal end of the optical transceiver module  10  is releasably coupled to a data transfer system bezel or wall  28  through threaded fastener members  29  attached to a flange after being inserted into a system access opening  30 . The connector end portion  26  has ports (not shown). The connector end portion  26  is to be coupled to a suitable push-pull duplex “SC” connector (not shown) in a known manner. While a duplex “SC” type connection is envisioned, a comparable end portion cooperable with other known connectors, such as for example, a single “SC” connector, a “LC” connector, or a “MT-RJ” connector can be used. 
   With reference to  FIGS. 2 to 5 , the optical transceiver module  10  comprises, a housing assembly  32  including a carrier member  34  being matable to a heat dissipating apparatus or heat sink cover or member  36 ; and, an electrooptical subassembly  38  that is substantially enclosed by and between the heat sink cover and carrier members  36  and  34 , respectively. The carrier member  34  and heat sink cover  36  can be made from a variety of suitable materials that are selected to ensure generally uniform heat dissipation yet maintain effective electromagnetic interference (EMI) shielding. The carrier member  34  has, preferably, an integral parallelepiped construction and can be fabricated from any number of suitable materials that are generally used for optical transceivers. Ideally, the carrier member  34  is made of a low-cost, die-cast metal, such as aluminum or zinc, or a plastic with a metallized coating. An upstanding peripheral wall  40  surrounds and, in part, defines an enclosure  42  ( FIGS. 3–5 ), which is a space between the carrier member  34  and the heat sink cover  36  for receiving the electro-optical assembly  38 . The upper surface of the wall  40  engages a bottom wall of the heat sink cover member  36  to maintain effective EMI shielding. The wall  40  does not extend across the proximal end of the carrier member  34  and this allows an end portion  43  of a printed circuit board  44 , forming a part of the electro-optical assembly  38 , to protrude out of the optical trarsceiver module. A pair of spaced apart and generally parallel pedestals  46  ( FIG. 5 ) is raised from the floor of carrier member  34  for purposes of providing a datum surface for the bottom surface of the heat sink cover  36 . A pair of L-shaped card mounting members  48 , only one of which is shown extends along each longitudinal mabginal edge of the optical transceiver module  10 . Each of the mounting members  48  defines a corresponding guiding channel  50  that is adapted to receive edges  52  ( FIG. 1 ) defining the slot  24 . A row of longitudinally spaced apart spring members  54  is attached to a bottom surface of each of the mounting members  48 . The spring members  54  serve to flexibly and resiliently bias the optical transceiver module  10  to the network adapter card  20  as well as permit bi-directional sliding motion of the optical transceiver module  10  to the network adapter card  20 . As noted above, the printed circuit board member  44  is sized and configured to mount within the enclosure  42  and has the end portion  43  extended slightly from the housing assembly  32  as illustrated in  FIGS. 2 to 4  for interconnection to the connector  16  (see  FIG. 1 ). The printed circuit board  44  may comprise any suitable type of rigid or flexible type substrate. A known type of card edge connector, not shown, is at the end of the printed circuit board  44  so as to register with the connector  16  in a known manner. The printed circuit board member  44  is formed with a pair of generally parallel and spaced apart cutouts  56  ( FIG. 5 ), each of which receives a respective one of the pedestals. As is known, this electrical connection is effective for interconnecting the electrooptical. assembly with the data transfer assembly. 
   Because of the heat generated due to operation of the electro-optical assembly  38 , it is important to maximize heat transfer therefrom. For instance, the laser driver chip  58  tends to operate at relatively higher temperatures than some of the other components on the printed circuit board  44 . One effective technique is to establish a thermal conductive path therefrom to the inside wall portion of the heat sink cover  36 . While the laser driver chip  58  is shown in an upstanding relationship from the printed circuit board  44 , it will be appreciated that other components have upstanding relationships, such as the known type of electro-optical transmitter subassembly (TOSA) unit  60  and an electro-optical receiver subassembly (ROSA) unit  62 . Both the TOSA  60  and ROSA  62  are wired to the laser driver chip  58  mounted on the printed circuit board  44 . 
   The heat sink cover  36  facilitates heat dissipation from operation of the electro-optical assembly  38 . In this embodiment, the heat sink cover  36  is generally thin and rectangular in overall shape. A plurality of heat dissipating elements or fins  64  project upwardly from an external surface thereof; for purposes of clarity only a portion of the fins  64  are illustrated in  FIG. 1 , but are more completely illustrated in  FIGS. 2–5 . The fins  64  are deployed in a generally parallel and spaced apart relationship in the manner illustrated. The fins  64  are generally uniformly spaced apart relative to each other to allow air flow therebetween for an effective convective cooling relationship. Of course, the present invention contemplates that the fins  64  can have other configurations, spacings and heights. In fact, the fins  64  need not substantially cover the upper surface area of the heat sink cover  36 . The proximal end of the heat sink cover  36  has a generally thin protective lip  68  extending over and beyond the protruding end portion  43  of the printed circuit board  44 . 
   The present invention includes one preferred embodiment of a coupling mechanism  70  that comprises a pair of coupling arms, coupling elements  72  adjacent a distal end portion of the heat sink cover  36 . Each of the coupling elements  72  is, preferably, formed integrally on opposing longitudinal edges of the heat sink cover  36  and is adapted to cooperate with cooperating structure  73  on a distal end of the carrier. A distal end portion  74  of each of the coupling elements  72  faces away and downwardly from the protective lip  68  for cooperation with corresponding elongated and curved slots  76  formed in sidewalls  40 . The slots  76  also form part of the coupling mechanism  70 . In this regard, each of the slightly curved slots  76  is sized and configured to allow for relative pivotal movement of the heat sink cover  36  with respect to the carrier member  34  when the coupling elements are inserted therein. Essentially, the slots  76  effect a camming action. The generally arcuate shape of the slots  76  effects a slight pivoting action of the heat sink cover  36  in a controlled path about a pivot axis  78  in response to the coupling elements  72  being inserted thereinto. Because of the camming provided by the slots  76  about the offset pivot axis  78  a controlled opening and closing motion of the heat sink cover  36  relative to the carrier member  34  and electro-optical assembly  38  is easily effected. This is accomplished with relatively substantially fewer components. Accordingly, the heat sink cover  36  is guided into the desired closed condition covering the enclosure  42  without imparting loading forces; especially lateral loading that might damage upstanding components of the electro-optical assembly  38 . As a consequence, during assembly and/or disassembly of the heat sink cover  36  the potential of damage to such upstanding components is greatly diminished if not eliminated by the coupling mechanism  70  of the present invention. Also, the width of each of the slots  76  has a slightly tapered configuration thereby facilitating an even more secure interconnection with the complementary sized and shaped coupling elements  72 . Such an interconnection minimizes compromise of EMI shielding integrity. In the broader context of the present invention, it will be appreciated that the coupling elements  72  could be on the carrier and the slots  76  provided in the heat sink cover  36 . 
   It will be noted in  FIG. 3  that the linear distance  79  the end portion  43  protrudes from the heat sink cover  36  is selected to be slightly less than the length of arcuate motion of the coupling elements  72  within each of the slots  76 , in order to permit the heat sink cover  36  pivotal movement without interfering with the circuit board  44  while the heat sink cover  36  is being assembled or disassembled. In addition, the heat sink cover  36  has a pair of straddle members  80  straddling and engaging longitudinal marginal edges of the circuit board  44  and act to engage the carrier end for effecting stoppage of the motion of the coupling elements  72  relative to the slots  76  during assembly/disassembly. A tight locking engagement of the coupling elements  72  within the slots  76  is effected ( FIG. 2 ) and as a result, effective maintenance of the EMI shielding is retained. 
   The embodiments and examples set forth herein were presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and use the invention. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. The description set forth is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings without departing from the spirit and scope of the appended claims.