Abstract:
An optoelectronic module is seated onto a substrate connector by guiding the module along an initial path portion that is misaligned with respect to the mating direction defined by the substrate connector and further includes providing a positive pressure drive along an end path portion with sufficient force to secure the optoelectronic module to the substrate connector. Where the mating is via a pin-and-socket arrangement, the positive pressure drive requires sufficient force to push the main body of the module to ensure entry of the pins into the sockets. Typically, there is a conversion from force applied in one direction to module motion in the orthogonal direction. However, a rocking cam embodiment is also described.

Description:
BACKGROUND ART  
       [0001]     Optoelectronic modules include circuitry for converting between signal processing/transmission in an optical mode and signal processing/transmission in an electrical mode. The conversion may be in a single direction, but many modules provide bidirectional conversions to enable data exchanges in both modes. Optoelectronic modules are used in telecommunications central offices and in centralized computing facilities, where there is a significant demand for high bandwidth communications. As compared to metal interconnects, such as copper wiring, optical interconnects offer benefits with regard to both bandwidth and performance (e.g., less skew), while satisfying requirements relating to eye safety, electromagnetic compatibility, reliability, manufacturability, and cost.  
         [0002]     It is common to couple an array of optoelectronic modules to a single substrate, such as a printed circuit board. Connectivity of a particular module is provided by coupling a module connector to a substrate connector. Edge-card style connectors are often used, but parallel optical links typically require the use of high-density electrical connectors to accommodate the larger number of electrical signals that must be managed. A single optical link may combine twelve optical channels that are separated into twelve electrical signals within the module. It follows that for each such link, there is a need for twelve electrical paths between the module and the substrate. Thus, the edge-card style connectors are sometimes replaced by connectors having pin-and-socket arrangements. The pins are rigid wire strands of electrically conductive material that are received within sockets having a fixed arrangement that corresponds to that of the pins.  
         [0003]     A greater degree of flexibility with regard to the maintenance of the telecommunications central office or the centralized computing facility is available if the optoelectronic modules are replaceable. A difficulty is that the openings for inserting and removing optoelectronic modules through the housing of the host system typically allow the greatest degree of freedom for module movement in the Z axis, i.e., the axis that is parallel to the surface of the substrate on which the substrate connectors are mounted. This is shown in  FIGS. 1 and 2 . A printed circuit board  10  having an electrical connector  12  is shown as being within the interior of a housing that includes a bezel, or faceplate  14 . The optoelectronic module  16  enters the housing through an opening within the faceplate, as indicated by the arrow  18  along the Z axis. However, the seating of the module must occur along the Y axis, which is represented by arrowed line  20 . The module connector  22  must properly seat onto the substrate connector  12 , but the direction of movement for seating the module is orthogonal to the greatest degree of freedom of module movement. Either before or after the module connector is seated, an optical fiber  21  is joined to the optoelectronic module to input/output optical signals.  
         [0004]     One solution is to mount a substrate connector that has a seating direction perpendicular to the printed circuit board  10  (i.e., along the Z axis). The module connector  22  must be relocated to the rear surface of the optoelectronic module  16 , rather than the bottom surface as shown in  FIGS. 1 and 2 . This allows the user to merely push the module rearwardly until the two connectors are seated together. This solution has benefits, but may impose restrictions on signal density. An alternative solution is described in U.S. Pat. No. 5,074,228 to Berg et al. Pressure contacts are preferably used for the connectors of Berg et al., rather than insertion contacts which require significantly more force in order to provide proper seating. The pressure contacts may be J-shaped leads which deflect slightly when press fit to contact pads of another connector. Since the required mating forces are reduced, the insertion force requirements are relaxed. The substrate connector of Berg et al. has a body that includes a guide member which is elongated along the Z axis. The elongated body of the substrate connector is surface mountable on a printed circuit board. The connector body also includes a camming element that is comprised of ramped regions. When the replaceable module is slid along the elongated body of the connector, a cam follower of the module raises and lowers the end of the module because of contact with the ramped regions of the camming element. While the raising and lowering of the module brings the module connector into contact with the leads of the substrate connector, the pressure contact may not be sufficient for some applications. Specifically, there may be concerns that less than all of the leads of the substrate connector have a low resistance connection to the contact pads of the module connector.  
       SUMMARY OF THE INVENTION  
       [0005]     The seating of an optoelectronic module onto a substrate connector includes guiding the module along an initial path portion that is misaligned from the mating direction of the substrate connector and includes providing a positive pressure drive along an end path portion with sufficient force to secure the optoelectronic module to the substrate connector. For applications in which the substrate and module connectors are electrical connectors that are coupled using a pin-and-socket arrangement, the positive pressure drive is enabled to push the main body of the optoelectronic module with sufficient force to ensure entry of the pins into the sockets.  
         [0006]     In a system for controlling the coupling of module connectors of a number of optoelectronic modules to an array of substrate connectors on a substrate, such as a printed circuit board, each optoelectronic module is associated with a device having a slide configured to receive the optoelectronic module so as to enable sliding movement of the module and includes a drive mechanism coupled to the slide to displace the slide toward and away from the substrate. In the sliding movement of the module, the module remains non-coplanar with the substrate connector to which it is to be coupled. However, the drive mechanism then displaces the slide toward and away from the substrate, with the displacement being such that the module connector is aligned to couple with the substrate connector.  
         [0007]     The method of controlling coupling of a module connector to a substrate connector may be described as including the step of sliding the optoelectronic module along a plane that is parallel to the substrate surface on which the substrate module is fixed. During this sliding movement, the module connector remains at a distance from the substrate surface such that the two connectors remain in a non-coplanar relationship. The method includes mechanically applying a coupling force to push the optoelectronic module toward the substrate in a controlled alignment to securely couple the module and substrate connectors. In a decoupling operation in accordance with the method, a decoupling force that is the reverse of the coupling force is mechanically applied to unseat the module connector from the substrate connector. The optoelectronic module is then slid along the same plane followed during the initial insertion, but in the reverse direction.  
         [0008]     As one possibility, the seating device includes a slide that remains stationary as the optoelectronic module is slid into place. The slide has a slide surface which defines the initial path portion for movement of the module. After the sliding action has been completed, a cam is pivoted to press the slide surface toward the substrate. A cam handle remains exposed to provide access by a user. When the cam handle is rotated in one direction, the connector of the optoelectronic module is seated to the substrate module. Rotation of the cam handle in the opposite direction unseats the connectors.  
         [0009]     In another embodiment, the seating device includes a sliding cam. The device has a slide that is perpendicular to the mating direction of the connectors. The positive pressure drive of the device includes an actuator and slots that are aligned with the mating direction. In this embodiment, movement of an actuator in the mating direction controls movement of the slide. For applications in which the substrate is mounted horizontally, the slide structure is moved horizontally to a position that aligns the substrate and module connectors and then is moved vertically to bring the two connectors into contact.  
         [0010]     In a rocking slide cam embodiment, the angle of the optoelectronic module varies with approach toward a seated condition of the connectors. For example, a number of actuator pins may be received within a corresponding number of grooves configured to determine the variation in module angle. In this embodiment, an actuator and the optoelectronic module may be in a fixed relationship with travel of the module along the initial path portion. However, the actuator is moved relative to the optoelectronic module during the end path portion, when the force is applied for seating the module connector with the substrate connector.  
         [0011]     The seating device also has a mechanical toggle switch embodiment. In this embodiment, linkage may be used to translate motion of an actuator along an axis that is perpendicular to the mating direction into motion of the optoelectronic module in the mating direction.  
         [0012]     The positive pressure drive may also be provided by a stroke multiplier mechanism in which motion of an actuator in a direction perpendicular to the mating direction is translated to motion in the mating direction by orientations of at least two slots. For example, a first slot in a fixed rail may have an orientation opposing a second slot in a movable slide. Additionally, vertical slots in the rail may be used to constrain the motion of the slide vertically, so that force applied to the actuator is desirably coupled to the slide. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a side view of an optoelectronic module to be seated within the interior of a host system.  
         [0014]      FIG. 2  is a side view of the optoelectronic module positioned above the connector to which the module is to be seated.  
         [0015]      FIG. 3  is a Z axis view of a force latch mechanism as one embodiment for seating an optoelectronic module in accordance with the invention.  
         [0016]      FIGS. 4, 6 ,  8  and  10  are front view of different steps in the operation of the force latch mechanism of  FIG. 3 .  
         [0017]      FIGS. 5, 7 ,  9  and  11  are rear views of the different steps for operating the force latch mechanism of  FIG. 3 .  
         [0018]      FIG. 12  is a perspective view of a sliding cam mechanism in accordance with a second embodiment of the invention.  
         [0019]      FIG. 13  is a side view of the sliding cam mechanism of  FIG. 12  with an optoelectronic module in a raised position.  
         [0020]      FIG. 14  is a side view of the sliding cam mechanism of  FIG. 12  with the module in its seated position.  
         [0021]      FIG. 15  is a rocking slide cam mechanism in accordance with a third embodiment of the invention.  
         [0022]      FIGS. 16-19  illustrate different steps in the operation of the rocking sliding cam mechanism of  FIG. 15 .  
         [0023]      FIG. 20  is a toggle switch mechanism in accordance with a fourth embodiment of the invention.  
         [0024]      FIGS. 21 and 22  are side views of steps for operating the toggle switch mechanism of  FIG. 20 .  
         [0025]      FIG. 23  is a side view of a stroke multiplier mechanism in accordance with a sixth embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0026]     The invention is a means for seating an optoelectronic module, such as the module  16  shown in  FIGS. 1 and 2 , to a connector  12  on a substrate  10 , such as a printed circuit board. A user is able to insert and withdraw the module through an opening in the faceplate  14  without withdrawing the substrate from the host system. In the embodiments to be described below, the module moves in the Z axis direction  18  before force is applied in the Y axis direction  20 , but the directions are not necessarily horizontal and vertical. While the seated connectors  12  and  22  will be described as being electrical connectors, in some applications the invention may be used to properly seat optical connectors. In such applications, the optical fiber  29  is replaced with electrical input/output members, since the module  16  is one in which conversions between an optical mode and an electrical mode are performed. As will be recognized by a person skilled in the art, the ability to connect and disconnect the fiber  29  may be replaced with a “pigtailed” module in which the fiber is fixed with respect to the module.  
         [0027]     A first embodiment of the seating device is shown in  FIG. 3 . This embodiment takes the form of a force latch mechanism  24  that is able to simultaneously apply force in two perpendicular directions so as to install or remove the optoelectronic module  16 . The mechanism includes a slide member  26 , a rail  28 , and a slide pin  30 . A recess  32  within the module  16  is aligned to receive the slide  26 . While not shown in  FIG. 3 , the module rests on the upper surface of the slide  26 .  
         [0028]     The module connector  22  is shown as being positioned above the substrate connector  12 . In operation, the module  16  slides along the top surface of the slide  26  with the two connectors remaining misaligned relative to the distance from the substrate on which the connector  12  resides. In the embodiment of  FIG. 3 , the substrate connector  12  includes an array of pins  34  that project upwardly for reception within a corresponding array of sockets within the module connector  22 . Alternatively, the socket-and-pin arrangement may be reversed.  
         [0029]      FIGS. 4 and 5  respectively show front and rear views of the force latch mechanism  24 , but without a module. For purposes of illustration, the slide  26  has been removed from the mechanism  24  in  FIG. 5 . A cam  36  is attached to the rail  28  at a sliding cam pin  38 . The cam includes a cam handle  40  that is accessible to a user during a seating or unseating operation.  
         [0030]     In a seating operation, the module is slid along the surface of the slide  26  to the position shown in  FIG. 3 . After the module is fully inserted, the user pushes the cam handle  40  in the direction indicated by arrows  42  and  44 . The initial movement of the module may be considered to be along the Z axis, but the orientation of movement is not critical to the invention.  
         [0031]     The force applied to the cam handle  40  causes the cam pin  38  to slide along the first path portion of a slot  46  within the rail  28 . When the cam pin reaches the end of the first path portion, the cam handle  40  may be pivoted upwardly such that the cam pin follows an arcuate second path portion of the slot  46 .  
         [0032]     The front and rear views of  FIGS. 6 and 7 , respectively, show the condition of the force latch mechanism  24  when the cam pin  38  has reached the end of the first path portion of the slot  46 . Because a fixed rail pin  48  engages a slot  50  within the cam  36 , the movement of the cam pin along the first path portion induces some pivoting, as indicated by arrow  52 . That is, the combination of the cam pin within the rail slot and the rail pin within the cam slot determines movement of the cam as the user applies pressure to the cam handle  40  of  FIG. 4 . The cam pin reaches the end of the first path portion simultaneously with the rail pin reaching the end of the cam slot. At this point, the cam contacts the slide pin  30  that is entrapped within a vertical opening  56 .  
         [0033]      FIGS. 8 and 9  illustrate the next step in the seating operation. Here, the cam is rotated as the user applies pressure to the cam handle (not shown). The cam rotates about the rail pin  48 . This forces the slide pin  30  to move downwardly within the vertical opening  56 , thereby displacing the slide  26  downwardly. Since the module is mounted to the slide, the module also moves downwardly.  
         [0034]     In  FIGS. 10 and 11 , the cam handle has been fully rotated. Consequently, the slide and module have been forced downwardly to achieve mating with the substrate connector  12  of  FIG. 3 . Sufficient force is provided to ensure that the pin-and-socket arrangement of the two connectors  12  and  22  provides low resistance coupling of the pins  34  with the optoelectronic module  16 .  
         [0035]     The steps for removing the optoelectronic module  16  of  FIG. 3  are the reverse of those described with reference to  FIGS. 4-11 . The cam handle  40  is rotated in a counterclockwise direction and is pulled rearwardly to the position shown in  FIG. 4 . This allows the module to be easily removed from the slide  26 . While the manipulation of the cam handle has been described as being manual, the force latch mechanism  24  may be adapted to hydraulic, pneumatic or electromechanical systems.  
         [0036]      FIG. 12  illustrates a second embodiment of the invention. In this embodiment, the seating device is a sliding cam mechanism  58 . The mechanism couples perpendicular motion by use of a slide  60  having diagonal slots  62  and  64 . A rail system is composed of the slide  60 , an actuator  66 , and a rail  68 . In this embodiment, the optoelectronic module  16  travels in the Z axis and engages the slide by means of a groove. The slide may be considered to be a sliding cam. The rail may be connected to the substrate by screws or other fasteners which pass through a pair of openings  70  and  72  within a bracket  74 .  
         [0037]      FIG. 13  shows the optoelectronic module  16  in a raised position, while  FIG. 14  shows the module in a fully seated position. Once the module is inserted, the actuator  66  accomplishes the Y axis (vertical) motion of the module by coupling the paths of various slots with the module. As best seen in  FIG. 13 , the actuator extends to a sliding member  76  that lies within a rail slot  78  of the rail  68 . The sliding member  76  has projections which extend into the diagonal slots  62  and  64  on the slide  60 . Since the slots extend diagonally upward, horizontal motion of the sliding member  76  and its projections is translated into vertical motion of the slide  60  and the module that is coupled to the slide. A pair of pins  80  and  82  extending from the slide project into vertical slots  84  and  86  within the rail  68 . As represented by arrow  88 , motion of the slide  60  is confined to the vertical by the use of the pins  80  and  82  within the vertical slots  84  and  86 . The vertical slide-rail constraint can be achieved in other manners, such as by the use of dovetail joints or folded edges that capture the slide.  
         [0038]     The operational steps of a third embodiment are illustrated in  FIGS. 15-19 . Here, the seating device is a rocking slide cam mechanism  98 . In this embodiment, the number of components is reduced, but the complexity of individual components is increased. A rail  90  receives the optoelectronic module  16 . The slots  92  and  94  within the rail are configured to cause the module to rock as pressure is applied to an actuator  96 . That is, rocking motion occurs as opposed to the straight vertical descent of the embodiment of  FIGS. 12-14 . The illustrated embodiment operates well with the MEG array connector known in the art.  
         [0039]     In  FIG. 15 , the optoelectronic module is inserted into the rocking slide cam mechanism  98 . A user can apply pressure directly to the module or to the actuator  96 . A rigid protrusion  100  extends beyond the module and initially rides within a slot groove  102 .  
         [0040]     The arrow  104  in  FIG. 15  represents the movement of the module  16  relative to the actuator  96  and the rail system  90 . After the module has been properly seated, the actuator is pressed inwardly, as represented by arrow  106  in  FIG. 16 . Within each slot  92  and  94  resides an actuator pin  108  and  110 . Immediately prior to the application of force to the actuator  96 , the actuator pins are at the ends of the slots, as shown in  FIG. 16 . As the module is pushed rearwardly, the two actuator pins  108  and  110  follow their respective grooves, but the grooves have different geometries such that the pins follow different paths.  
         [0041]     Referring now to  FIG. 17 , when the protrusion  100  at the end of the module  16  clears the slot groove  102 , the rear of the module is no longer supported by the rail system  90 . However, the two actuator pins  108  and  110  control the position of the module by means of their engagement with the respective slots  92  and  94 . The slots in the rail system are designed such that the module exhibits a slight tilt, which is intended to accommodate the high mating force required for high density electrical connectors.  
         [0042]     The rearward movement of the module  16  causes the protrusion  100  to abut a hard stop  112 . The contact of the protrusion with the hard stop prevents any further movement of the module along the Z axis (arrow  106 ). In this embodiment, the actuator is able to release from its neutral position, so as to be movable relative to the module. As the user continues to push the actuator  96 , the actuator moves relative to the module, as represented by arrow  114  in  FIG. 18 . Movement of the module tracks the geometries of the slots  92  and  94 . The module is forced downwardly to mate with the electrical connector (not shown). In  FIG. 19 , the actuator  96  has reached its final position. In this position, the module  16  is locked into its seated position with no tilting. An unseating operation follows the reverse of the seating operation.  
         [0043]     The geometry of the slots  92  and  94  can be designed to accommodate any type of connector. Thus, the principle may be modified for any particular application.  
         [0044]      FIG. 20  illustrates a toggle switch mechanism  116  in accordance with another embodiment of the invention. The mechanism includes an actuator  118 , a rail  120 , and a slide  122 . The cooperation of components converts the Z axis motion of the actuator  118  into Y axis translation of the module  16  by means of links  124  and  126 . Each link has a first end that is pivotally connected to the actuator, such that the first ends move linearly with the actuator, but are able to rotate. The opposite end of each link is coupled to a vertical slot  128  and  130  within the rail. A bracket  132  may be used to mount the mechanism to a substrate, such as a printed circuit board.  
         [0045]     As best seen in  FIG. 21 , the rail  120  includes a second pair of vertical slots  134  and  136 . Engaging each slot is a projection  138  and  140  that is fixed to the slide  122  that supports the module  16 . The engagement of the projections with the vertical slots limits the movement of the slide  122  to vertical movement. The mechanism is shown in the raised position in  FIG. 21 . In this position, the projections  138  and  140  are at the upper extents of the slots  134  and  136 . Also, the links  124  and  126  are at only a slight decline.  
         [0046]     The slide  122  has a pair of diagonal grooves  142  and  144 . The movement of the actuator  118  is coupled to the slide  122  by means of the grooves. For example, the pivoting ends of the links  124  and  126  may be secured by pivot pins having ends that extend into the diagonal grooves. Thus, as the actuator is pushed inwardly, the links will pivot at their upper ends and will ride along the respective slots  128  and  130  at the their lower ends. Simultaneously, the pivot pins through the upper ends of the links will travel along the diagonal grooves  142  and  144  to apply downward pressure on the slide  122 . This causes the projections  138  and  140  from the slide to travel downwardly along the second pair of vertical slots  134  and  136  within the rail  120 . Eventually, the mechanism will reach its lowered position shown in  FIG. 22 , with the connector of the module  16  properly seated to the substrate connector (not shown).  
         [0047]     Yet another embodiment is shown in  FIG. 23 . The stroke multiplier mechanism  146  includes an actuator  148 , a slide  150 , and a rail  152 . The optoelectronic module  16  is shown as resting in position on the slide. In this figure, the coupler  154  for receiving an input/output optical fiber is included. A pair of opposing diagonal slots  156  and  158  multiply the motion of the input actuator  148 . The first of the diagonal slots  156  is in the fixed rail  152 , while the second slot  158  is in the movable slide  150 . Vertical slots  160  and  162  constrain the motion of the slide vertically. The vertical slots may be either in the rail or the slide. After the module has been engaged to the slide, it is also restricted to vertical movement.  
         [0048]     By modifying the angle of the opposing diagonal slots  156  and  158 , it is possible to adjust the stroke multiplication to the degree required for a particular connector. The sliding cam mechanism  58  of  FIG. 12  may be considered to be a specific embodiment of a stroke multiplier, if one of the “opposing slots” is identified as the horizontal rail slot  78 .  
         [0049]     While a number of mechanisms have been described and illustrated for converting the direction of motion orthogonally so as to seat an optoelectronic module, the invention extends beyond the illustrated embodiments. Moreover, the conversion need not be directly orthogonal, as can be seen by the rocking slide cam mechanism of  FIGS. 15-19 , which takes advantage of module tilting to provide the force necessary to properly mate the module connector to the substrate connector.