Abstract:
The optical pluggable transceiver according to the present invention has features of a good heat dissipating function with a simplified configuration thereby reducing the cost of not only the component used but also the process itself. The transceiver of the present invention comprises a resin frame, an optical subassembly, a electronic substrate, both mounted on the frame, a heat dissipating member, made of metal, for conducting and radiating heat generated by the electronic circuit on the substrate, and a metal cover for putting these frame, subassembly, substrate, and heat dissipating member therein. A greater part of the surface of the heat dissipating member exposes from the cover, accordingly, the efficiency for radiating heat may be improved. Moreover, these members of the frame, the optical subassembly, the substrate, the heat dissipating member, and the cover are assembled only by fitting without screwing or gluing. Accordingly, the manufacturing process of the transceiver can be extremely simplified.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The present application claims the benefit of the provisional application Ser. No. 60/622,690, filed Oct. 28, 2004; and the provisional application Ser. No. 60/622,802, filed Oct. 29, 2004. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a new releasing mechanism of the pluggable transceiver from the cage. 
   2. Related Prior Art 
   The pluggable optical transceiver (hereinafter denoted as transceiver) is installed on the host system such that a cage, which is made of metal and has a box shape with one end being opened and protruded from the face panel of the host system, receives the transceiver in the open end thereof to expose the optical receptacle provided in the front end of the transceiver from the face panel of the host system. The optical receptacle receives an optical connector accompanied with an optical fiber. Thus, the optical fiber may optically couple with an optical device installed within the transceiver and establish the optical communication between the fiber and the optical device. 
   The cage provides an electrical connector in the deep end thereof, while the transceiver provides, in a rear end thereof, an electrical plug to mate with the electrical connector in the cage. By inserting the transceiver into the cage, the electrical plug of the transceiver comes to mate with the electrical connector, which enables the transceiver to communicate with the host system, namely, exchanging the electrical information and supplying the electrical power from the host system to the transceiver. Moreover, by setting the electrode of the plug in a preset configuration, the transceiver can be optionally inserted into or removed from the cage as the host system is powered on, which is the so-called hot-pluggable function. 
   One type of such pluggable transceiver has been specified in a multi-source agreement (MSA) as “Small Form-Factor Pluggable (SFP) Transceiver Multi Source Agreement” published through the internet &lt;http://www.shelto.com/SFP/SFP MSA.pdf&gt;. However, this MSA merely specifies the fundamental electrical specification, the pin-assigning, and the physical dimensions, rules no substantial architecture. The MSA only ensures that, as long as the transceiver satisfies the agreement, the transceiver can be installed within the cage and show the fundamental performance. Recently, the optical communication may be available in personal, namely, the optical fiber is brought to the independent home, and an optical transceiver that satisfies the agreement with the cost thereof further reduced has been requested. 
   The U.S. Pat. No. 6,744,963, has disclosed one type of engaging mechanism with a bail and an actuator of the pluggable transceiver. Rotating the bail, which has a U-shaped configuration to put the optical receptacle between two legs thereof, around the center formed in a middle of the legs, the actuator may slide backward working together with the bail&#39;s rotation. The actuator has a tapered surface in the rear end thereof. The tapered surface slips under the latch tab of the cage by the sliding of the actuator to push up the latch tab, accordingly, the transceiver may be released from the cage. 
   Another U.S. Pat. No. 6,439,918, has disclosed another configuration of the releasing mechanism that also comprises of the bail and the actuator. The actuator in this prior art is attached, in the center portion thereof, to the body of the transceiver. The actuator may move in a seesaw motion by the attached portion as the center of the motion. Rotating the bail, the bail pushes out the forward arm of the actuator, which pulls in the rear arm of the actuator by the seesaw motion thereof. Since the rear arm forms a projection in the tip thereof to be engaged with the cage, the transceiver may be released from the cage. 
   Still another U.S. Pat. No. 6,430,053, has disclosed a releasing mechanism comprised of a bail and a base. The bail has a shaft working together with the rotation of the bail. In the end of this shaft is provided with a projection having a tapered surface. The shaft slides backward as rotating the bail to slip under the latching tab of the cage to push up the tab. Accordingly, the engagement between the transceiver and the cage may be released. The releasing mechanism of this prior art is so similar to those described in the U.S. Pat. No. 6,744,963. 
   Recently, an optical hub system has been proposed and developed in part, in which a plurality of cages is densely arranged in vertical and horizontal. In such system, the gap to the nearest cage becomes only a few millimeters. When the pluggable transceiver is inserter into or removed from such densely arranged cages, the grip of the bail cab no be occasionally handled. In one example, when cages neighbor to the target transceiver receive other pluggable transceivers with an optical connecter and an optical cable accompanied with the optical connector, these optical cables and connectors disturb to handle the grip of the target transceiver. 
   To release the target transceiver is necessary to release neighbor transceivers, or to use some special tools to bring out the target transceiver from the cage, which makes it troublesome and occasionally breaks the transceiver, or the optical connector. Moreover, for the transceiver with the bail to release from the cage by rotating in the front of the receptacle, the neighbor transceivers, or the neighbor connectors with the cable disturbs even to touch the bail. 
   SUMMARY OF THE INVENTION 
   The optical pluggable transceiver according to the present invention has a feature that the transceiver provides an optical receptacle, a bail and an actuator. The bail is assembled with the optical receptacle to surround the receptacle and to be able to rotate so as to traverse the receptacle. The bail of the present invention extends in the front of the receptacle greater than that in the top or the bottom. The actuator includes a rotational axis and two arms putting the axis therebetween. Each arm may move in a seesaw motion by the rotational axis as a center of the motion, namely, one arm moves in up-and-down cooperating with the rotation of the bail, while the other arm with a projection to be engaged with the cage may move in down-and-up, accordingly, the engagement between the transceiver and the cage can be released. 
   Since the bail of the transceiver is thus configured, the target transceiver can be handled even when, in the cages being densely arranged hub system, the cages neighbor to the target one receive the optical transceiver with the optical connector and the optical cable, the target transceiver can be accessed in the grip or the bail thereof to bring out from the cage in ease. Merely increasing the room for the bail to protrude from the receptacle, it may be enough to lengthen the leg of the bail. In such configuration, the protrusion from the top, or from the bottom, of the receptacle also increases, which deviates the transceiver from the agreement. On the other hand, to move the rotational center of the bail close to the edge of the receptacle also widens the room of the bail at the front of the receptacle. However, this configuration deviates from the standard of the optical connector because the bail exists in the space where the optical connector should be received. The mechanism according to the present invention can dynamically expand the room where the bail extends at the front of the receptacle as satisfying the agreement according to the pluggable transceiver and the standard according to the optical connector 
   Specifically, the bail comprises a pair of legs and a grip portion connecting the legs. The leg forms a first guide projection in a portion between the tip of the leg and the grip portion, while the second guide projection in the tip thereof. The optical receptacle forms a first guide groove for receiving the first guide projection and a second guide groove for receiving the second guide projection. The first guide groove configures in a line with a starting point and an ending point, while the second guide groove configures an arc whose center locates in a virtual point extending the first guide groove. 
   Since two guide grooves are thus configured, the bail can stand in vertical at both the top and the bottom of the transceiver, and increase the room at the front of the receptacle. The second guide groove is not restricted to the arched shape, and may be in linear by accepting the standstill at the top or the bottom of the receptacle not vertical thereto. Moreover, even when the standstill at the top or the bottom may be maintained, the shape of the second guide groove is not restricted to the arch. It is the only condition to set the bail stable in the vertical position that the starting point of the first guide groove locates in a position vertical to the starting portion of the first guide groove. 
   Moreover, the bail of the present invention provides a cam with a major surface accompanied with a major axis thereof and a minor surface with a minor axis and the center of the cam coincides with that of the first guide projection. The actuator, in one arm thereof, forms a sliding surface to come in contact to the cam. When the first guide projection locates in the starting point in the first guide groove, the minor surface of the cam touches the sliding surface of the actuator, and the other arm of the actuator, the tip thereof having a latching projection, is pushed out this latching projection. On the other hand, when the first guide projection moves to the end point in the first guide groove, the major surface of the cam pushes out the sliding surface of the actuator and the latching projection may be pulled in the transceiver to release the engagement between the latching projection and the cage. 
   The transceiver of the present invention further provides a metal cover that includes a support fin to support the actuator from the downward. By a resilient force inherently attributed to the metal plate, the one arm with the sliding surface is pushed to the optical receptacle. Accordingly, the bail becomes stable in the position where the first guide projection locates in the stating portion in the first guide groove, that is, the minor surface comes in contact to the sliding surface. In this position, the latching projection is pushed out from the transceiver to engage with the cage. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1A  is a perspective diagram viewed from the top of the transceiver, and  FIG. 1B  is a perspective diagram viewed from the bottom of the transceiver; 
       FIG. 2  is an exploded view of the transceiver according to the present invention; 
       FIG. 3A  is a perspective view of the heat dissipating member,  FIG. 3B  is a perspective view of the frame, and  FIG. 3C  is a side view of the frame assembled with the heat dissipating member; 
       FIG. 4  shows a process for assembling the substrate, which is built with the sub-assemblies, with the frame; 
       FIG. 5  is a perspective diagram, which is viewed from the rear, of the frame assembled with the sub-assemblies and the substrate; 
       FIG. 6  schematically shows the mechanism that the rear fitting post presses the substrate forward; 
       FIG. 7A  is a cross section showing the sub-assemblies mounted on the frame, and  FIG. 7B  is a perspective view of the frame and the sub-assemblies mounted on the frame; 
       FIG. 8A  and  FIG. 8B  are perspective diagrams of the finger member viewed from the rear top and the front bottom, respectively, and  FIG. 8C  and  FIG. 8D  are perspective diagrams of the finger member assembled with the frame viewed from the top and the bottom, respectively; 
       FIG. 9A  schematically shows the rotational mechanism of the first conventional combination of the bail and the frame, and  FIG. 9B  is a second rotational mechanism of the bail and the frame; 
       FIG. 10  schematically shows the rotational mechanism of the bail and the frame according to the present invention; 
       FIG. 11A  is a perspective view of the bail and the actuator of the present invention when the bail is in the top of the optical receptacle, and  FIG. 11B  is a side view showing the same situation of the bail as  FIG. 11A ; 
       FIG. 12A  is a perspective view of the bail and the actuator when the bail is in the front of the optical receptacle, and  FIG. 12B  is a side view showing the same situation of the bail as  FIG. 12A ; 
       FIG. 13A  is a perspective view of the bail and the actuator when the bail is in the bottom of the optical receptacle, and  FIG. 13B  is a side view showing the same situation of the bail as  FIG. 13A ; 
       FIG. 14  is a bottom view of the transceiver inserted into the cage; and 
       FIG. 15  is a cross section of the completed transceiver taken along the ling A-A in  FIG. 1A . 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Next, preferred embodiments of the optical transceiver according to the present invention will be described as referring to accompanying drawings. In the drawings and the explanations, the same symbols and the same numerals will refer the same elements without overlapping explanations. The present invention provides an optical transceiver, which solves the subjects not only to maintain the heat dissipating performance and ensure the widest area for mounting the components but also to reduce the number of the components as reducing the cost themselves, in addition to simplify the assembly of the components, accordingly, to decrease the production const thereof. 
     FIG. 1A  is a perspective diagram of the transceiver  1  viewed from the top thereof, while  FIG. 2A  is a diagram viewed from the bottom. The optical transceiver  1  has a rectangular parallelepiped shape, the forward end of which forms an optical receptacle  1   a , while the rear end forms an electrical plug  17   a , which mates with the electrical connector mounted on the host system, provided on a substrate  17 . Here, the front and the rear corresponds to a side where the optical receptacle  1   a  is formed and to a side opposite thereto, respectively, for the description sake. The transceiver provides, in addition to the optical receptacle  1   a , the bail  11  and the actuator  12  in the front. The frame  14  installs the substrate  17  in the rear, while the forward thereof forms the optical receptacle  1   a  in a body as holding the actuator  12  and the bail  11 . The projection  12   a  of the actuator  12  and a plurality of fingers of the finger member  13  exposes and protrude from the front end of the cover  19 . The projection  12   a  comes to mate with the opening in the cage to fix the transceiver  1  to the cage. The bail  11  and the actuator  12  provide the function to release this mating between the transceiver  1  and the cage. The fingers  13   a  stabilize the ground potential of the transceiver  1  and provide paths for dissipating heat to the outside thereof by coming in contact to the inside of the cage when the transceiver is inserted into the cage. 
     FIG. 2  is an exploded diagram of the transceiver  1  viewed from the bottom thereof. Here, the bottom corresponds to a side where the bail  11  and the actuator  12  are attached thereto, while the top corresponds to an opposite side. The frame  14 , made of resin, is integrated in a body with the optical receptacle  1   a . The frame is plated in entire surface thereof with metal to ensure the shielding of the transceiver  1 . The frame  14  assembled with the heat dissipating member  18 , which has a configuration to fit to the frame  14 , the bail  11  and the actuator  12  in the front side. As explained later in this specification, the substrate  17  is assembled with the frame  14  by positioning at six points after electrically connected with a transmitting optical subassembly (TOSA)  15  and a receiving optical subassembly (ROSA) by using a positioning tool. The finger member  13  is fixed to the frame by winding around the frame  14  at a position where the TOSA  15  and the ROSA  16  are installed and sliding the cover  19  to wrap the edge of the finger member  13 . The cover  19  is slid from the rear to put the heat dissipating member  18 , the frame  14  and the substrate  17  therein. 
   Next, details of the heat dissipating member  18  and the process for assembling the transceiver  1  of the present invention will be described. 
   Assembly of the Frame with the Heat Dissipating Member 
     FIG. 3A  is a perspective view of the heat dissipating member  18 ,  FIG. 3B  is a perspective view of the frame  14 , and  FIG. 3C  is a side view of the frame  14  assembled with the heat dissipating member  18 . 
   The heat dissipating member  18 , having a substantially rectangular plan view, includes first to third portions,  18   a  to  18   c , from the front side of the transceiver  1 . The second portion  18   b  is thicker than the other two portions,  18   a  and  18   c . The tip of the first portion  18   a  forms a rib  18   e , while the tip of the third portion  18   c  forms another rib  18   f . The width of the former rib  18   e  is narrower than the latter rib  18   f . Moreover, the rear end of the second portion  18   b , i.e. at the boundary between the second and third portions,  18   b  and  18   c , form a hooked projection  18   d . As shown later, the thicknesses of these first to third portions,  18   a  to  18   c , trace the cross-sectional shape along the longitudinal direction of the frame  14 . 
   The heat dissipating member  18  is formed by the metal extrusion method. Metal used for the heat dissipating member  18  is preferable to have a thermal conductivity greater than 60 Wm/K, and the present transceiver applies aluminum. The cross section of the heat dissipating member  18  along the longitudinal axis of the transceiver  1  traces that of the frame  14 . Die-casting or processing of sheet metals is typically applied to form components with complex structures. However, the die-casting has a disadvantage from the cost viewpoint, while the latter, the processing of the sheet metal, has inferior to ensure the flatness. The heat dissipating member  18  of the present invention is formed by the metal extrusion method, which makes the cost merit and the stiffness of the component inconsistent. 
   As shown in  FIGS. 3A and 3C , the hooked projection along the longitudinal axis of the transceiver  1  mates with the overhang in the cross section thereof, which realizes the fitting configuration. However, the heat dissipating member  18  is not fixed along the transverse direction. By setting the cover  19  to put the frame  14  and the heat dissipating member  18  therein, and by fixing the cover  19  to the member  18 , the heat dissipating member  18  is fixed to the frame  14 . The cover  19  exposes the top of the transceiver  1 , namely, the top of the transceiver  1  exposes the surface  18   h  of this heat dissipating member  18 . 
   The frame  14 , formed by the injection molding, includes first to fourth portions,  14   a  to  14   d , from the front side to the rear side. The first portion  14   a  forms two optical receptacles  1   a , each corresponding to the optical transmission and the optical reception, respectively. The inner dimension of the receptacle  1   a  is strictly decided by the standard of the optical connector to mate with this receptacle  1   a . The second portion  14   b  mounts the TOSA and the ROSA,  15  and  16 . On the top of this second portion  14   b  is formed with two openings,  141  and  142 , to bury thermal sheets to couple the OSAs,  15  and  16 , in thermal with the first portion  18   a  of the heat dissipating member  18 . The thermal sheets, which are not shown in figures, may thermally couple the OSAs,  15  and  16 , with the member  18  by ensuring the heat dissipation path from the stem,  15   c  and  16   c , which mount the semiconductor devices thereon, to the heat dissipating member  18 . Between the first and second portions,  14   a  and  14   b , forms a projection  14   g  in the side thereof to latch the cover  19 . By engaging this projection  14   g  with the opening provided within the latch tab  19   a , the cover  19  is latched with the frame  14 . 
   The third portion  14   c  mounts the substrate  17  thereon. That is, the third portion  14   c  provides the first type of post,  14   e  and  14   f , for engaging with the substrate  17  and the other type of post  14   h  for abutting against the substrate  17 . As shown in the later, to fit notches and steps formed in respective sides of the substrate  17  to these posts,  14   e ,  14   f  and  14   h , fixes the substrate  17  to the frame  14 . The fixing is carried out only by the fitting those posts in the frame  14  to corresponding structures in the substrate  17 , without any screws or adhesive. 
   The bottom surface  18   g  of the second portion  18   b  of the heat dissipating member  18  comes in contact to the component, such as ICs, mounted on the substrate  17  via a thermal sheet, which ensures the heat dissipating path from the IC to the member  18 . Between the third and fourth portions,  14   c  and  14   d , is formed with an overhang  14   m  to fix the heat dissipating member  18  to the frame  14 . The hooked projection  18   d  engages with this overhang  14   m , which assembles the heat dissipating member  18  with the frame  14 . The position of the heat dissipating member  18  along the longitudinal direction is defined by two ribs,  18   e  and  18   f , while the up-and-down direction thereof is defined by putting the frame  14  and the member  18  within the cover  19  after temporally engaging this hooked projection  18   d  with the overhang  14   m.    
   The fourth portion  14   d  forms a groove  14   k  to engage with the rib  18   f  in the rear end of the heat dissipating member  18 , while between the first and second portions,  14   a  and  14   b , is formed with another groove  14   l  to receive the rib  18   e  in the front end of the member  18 . The heat dissipating member  18  is assembled with the frame  14  by sliding thereof along the transverse direction of the transceiver  1  as two ribs,  18   e  and  18   f , insert into corresponding grooves,  14   l  and  14   k , and the hooked projection  18   d  mates with the overhang  14   m . As shown in later, the top surface  18   h  of the heat dissipating member  18  exposes outside even after setting the cover  19 . Accordingly, the radiative efficiency to the cage may be maintained. Moreover, some cages occasionally provide a movable fin for radiating the heat, the heat dissipating member  18  of the present transceiver may come in directly contact to such movable fin, which realizes the most effective heat dissipating function. In the explanation above, the assembly of the heat dissipating member  18  with the frame  14  is carried out in advance to that of the substrate with the frame  14 . However, it may be applicable to assemble the heat dissipating member  18  with the frame  14  after the assembly of the substrate  17  with the frame  14 . 
   Assembly of the Substrate with the Frame 
   The assembly of the frame  14  with the substrate  17  is performed by four fitting mechanisms and two positioning mechanisms.  FIG. 4  shows the process of this assembly. In  FIG. 4 , the frame  14  provides the heat dissipating member  18  in advance to the assembly with the substrate  17 . 
   First, the substrate  17  is connected to the OSAs,  15  and  16 , before assembled with the frame  14 . The OSAs,  15  and  16 , each provides the sleeve,  15   a  and  16   a , in the front side thereof, while the stems,  15   c  and  16   c , in the rear side thereof. The stem,  15   c  and  15   c , extrudes a plurality of lead pins,  15   d  and  16   d , in rearward to connect to the corresponding electrode on the substrate  17  in electrical. On the stem,  15   c  and  16   c , is installed with a laser diode (LD) for the TOSA  15 , while, for the ROSA, the stem  16   c  installs a photodiode (PD) and a preamplifier for amplifying electrical signal generated by the PD. On the root of the sleeve,  15   a  and  16   a , is formed with a pair of flanges,  15   b  and  16   b , which positions the OSAs,  15  and  16 , with respect to the frame  14  along the longitudinal direction by sandwiching the walls,  14   n  and  14   p , formed in the second portion  14   b.    
   The substrate  17  has a width substantially equal to that of the transceiver  1 . Although not explicitly shown in  FIG. 4 , the rear end thereof forms a plurality of electrodes for the electrical plug  17   a . On both sides of the substrate  17  are formed with notches  17   b , and steps  17   d . These four structures and the front end  17   h  determine and position the substrate  17  on the frame  14 . The substrate  17  mounts a plurality of ICs,  20   a  and  20   b , resistors, and capacitors. Although not shown in  FIG. 4 , the opposite surface of the substrate  17  also mounts the IC  20   c  and some electrical components. As shown in later, the heat dissipating member  18  may thermally couple with the IC  20   c  mounted on the opposite surface facing the member  18 . 
   The frame  14  forms the first type of posts,  14   e  and  14   f , in the side of the third portion  14   c  and in the side between the third and forth portions,  14   c  and  14   d , respectively. Further, the frame  14  forms the second type of posts  14   h  in the center and the side at the boundary between the second and third portions,  14   b  and  14   c . Since the outside dimension of the substrate  17  inherently accompanies with a tolerance of around 0.1 mm, these posts are required, in order to anchor the substrate as ensuring the enough engaging strength, to be tall enough to deform and to compensate such tolerance, when the substrate  17  is to be fit to the frame  14 . However, the multi source agreement (MSA) concerning to this transceiver rules the height thereof, accordingly, the post is limited in the height thereof and does not provide an enough margin to fit the substrate  17 . In the present transceiver  1 , the first type of post  14   e  formed in the forward accompanies with a beam  14   s  beneath the post  14   e  and, by deforming this beam  14   s  in torsional, the post  14   e  deforms enough to compensate the tolerance and to ensure the engaging force with the substrate  17 . 
   For instance, when the beam  14   s  has a cross section of 2.4 mm in the height by 0.8 mm in the width, and is made of resin with a modulus of the transverse elasticity and an allowable shearing stress being 48 MPa and 80 MPa, respectively, the post  14   e  can be deformed by 0.5 mm in the tip thereof for the length of the post  14   e  of 4.5 mm by configuring the beam length longer than 3 mm in both of the front and the rear of the post  14   e . That is, the engaging length can be ensured greater than 0.5 mm. 
   For the post  14   f  in the rear side of the transceiver  1 , the frame  14  forms, in a center thereof, a groove  14   q  with a thinner wall to deform the post  14   f  enough when the substrate  17  is fit into the frame  14 . That is, by bending at this groove  14   q , the distance between the posts  14   f  may be widened to fit the substrate  17 , which reduces the resistant force for the insertion of the substrate  17  and enhance the productivity. By setting the rear of the substrate  17  as abutting the front edge  17   h  against the second type of posts  14   h , the notch  17   b  engages with the post  14   e  and the side  17   g  of the step  17   d  is fit in the side of the other post  14   f.    
   On the other hand, for the longitudinal direction of the substrate  17 , by abutting the other surface of the post  14   f  against the step  17   d , the substrate  17  may be put between the first type of post  14   f  and the second type of post  14   h . The tip of respective posts,  14   e  and  14   f , form hooks,  14   u  and  14   v , accordingly, once set the substrate  17  to the posts,  14   e  and  14   f , the substrate  17  is hard to disassemble with the frame  14 . 
     FIG. 5  illustrates the frame  14  assembled with the substrate  17  viewed from the rear. The first type of posts,  14   e  and  14   f  thereto, sandwich the substrate  17  and influence the resilient force by the deformation of the frame  14 . Further, both sides  14   w  of the rear groove  14   q  shapes in arc to provide a room to bend the frame  14  so as to expand the distance between posts  14   f , which makes it easy to set the substrate  17  in the frame  14 . 
     FIG. 6  illustrates the mechanism to fix the substrate  17  to the frame  14  along the longitudinal direction. The substrate  17  is set to the frame  14  as pressing the post  14   f  rearward. Once setting to the frame  14 , the post  14   f  presses the substrate  17  forward, which fixes the substrate  17  to the frame  14 . Specifically, the post  14   f  leans forward by about 0.2 mm before receiving the substrate  17 . After setting the substrate  17  as abutting the front edge  17   h  thereof against the second type of post  14   h , the post  17   f  deforms to the shape shown in  FIG. 6 , i.e., substantially perpendicular to the primary surface of the frame  14 . In this position, the post  14   f  presses the substrate  17  by;
   F= 3 EIε/L   3 . 
Where E and I are Young&#39;s modulus and the second moment of area of the resin material of the frame  14 , respectively, ε is the displacement, and L is the height of the post. By setting the height L and the cross section of the post  14   f  not to exceed the permissible stress for the displacement ε, the magnitude of the force to press the substrate  17  forward may be optionally determined. Moreover, the present optical transceiver  1  provides a groove  14   t  just front of the post  14   f  to adjust the height thereof.
 
   The optical transceiver  1  thus configured may install the substrate  17  only by the frame  14  without any other components. Moreover, (1) to hold the substrate  17  in flexible along the longitudinal direction may relax the thermal stress due to the discrepancy in the linear expansion between the substrate  17  and the frame  14 , (2) the substrate  17  once set on the frame  14  does not loose and has an improved positional accuracy because the substrate  17  is held by the frame  14  such that the post  14   e  puts the substrate  17  along the transverse direction while the other posts  14   f  sandwiches the substrate  17  along the transverse direction and, cooperated with the post  14   h , along the longitudinal direction, and (3) the thermal sheet may be put between the heat dissipating member  18  and the IC  20   c  because the substrate  17  is assembled with the frame  14  only by fitting. 
   Assembly of the OSA with the Frame 
   The transceiver  1  of the present invention enhances the productivity by assembling the OSA with the frame  14 , similar to the assembly of the substrate  17  with the frame  14 , only by fitting without any member to fix the OSAs,  15  and  16 , to the frame  14  such as a holder.  FIGS. 7A and 7B  illustrates the OSAs,  15  and  16 , assembled with the frame  14 , in a cross section thereof ( FIG. 7A ) and a perspective view ( FIG. 7B ). These figures,  FIGS. 7A and 7B , correspond to those viewing forward from the partition walls,  14   n  and  14   p , in  FIG. 4 . The wall,  14   n  and  14   p , form a finger  14   y . The OSAs,  15  and  16 , having a cylindrical shape, are fit to the preset positions from the upper in the drawing, from the bottom side of the transceiver  1  in the practical configuration. The gap d between the finger  14   y  and wall facing thereto is slightly smaller than the diameter of the grip portion between two flanges,  15   b  and  16   b . The OSAs,  15  and  16 , may be set into the position because not only the grip portion thereof expands this gap d but also the distance between two OSAs,  15  and  16 , may be widened within the flexibility of the lead pins,  15   d  and  16   d . Moreover, the OSAs,  15  and  16 , once set in the frame  14  are hard to disassemble as long as the gap d is manually expanded even the frame  14  with OSAs,  15  and  16 , is held in upside-down, because the finger  14   y  recovers its original position due to the resilient characteristic of the resin member of the frame  14 . 
   The longitudinal position of the OSA may be determined by sandwiching the partition wall,  14   n  and  14   p , with the flanges,  15   b  and  16   b . As shown in later, the finger member  13  is inserted between a gap between this wall,  14   n  and  14   p , and the rear flange,  15   b  and  16   b . Thus, the OSA is automatically positioned and fixed with respect to the frame  14  without any additional components. 
   Assembly of the Finger Member 
     FIG. 8A  is a perspective drawing viewed from the front of the finger member  13 , while  FIG. 8B  is a perspective drawing viewed from the rear. The finger member  13 , made of stainless sheet with a thickness of about 0.1 mm only by cutting and bending, includes four sides,  13   c  to  13   e , forming a box with a slit  13   h  in one side  13   e . A plurality of fingers  13   a  protrudes from the side  13   c , and other fingers  13   b  protrude from the bottom  13   d . Here,  FIG. 8B  and  FIG. 8D  illustrates the finger member  13  in upside-down 
   The bottom  13   d  is bent inward to form the piece  13   f  at a side opposite to that protruding the fingers  13   b , while, the top  13   e  is also bent inward to form the piece  13   g . The width of the top  13   e  is narrower than that of the bottom  13   d . As described in later, these two pieces,  13   f  and  13   g , are sandwiched between frames  14  and between the frame and the heat dissipating member  18 , respectively, to fix the finger member  13  to the frame  14 . Moreover, the bottom  13   d  provides a plurality of projective tabs  13   i , and the side  13   c  forms, in addition to the finger  13   a , a plurality of supplemental fingers  13   j . These projective tabs  13   i  and supplemental fingers  13   j  come in contact to the cover  19 , which effectively shields the transceiver  1  by increasing a count of contact. 
   In order to ensure the firm contact to the cage and to enhance the EMI shield, the finger member  13  should be short as possible in the finger thereof in addition to increase the count of the finger. Accordingly, the present transceiver  1  provides the finger member  13  that has a plurality of fingers,  13   a  and  13   b , independent of the cover  19 , and the finger member  13  surrounds the optical receptacle  1   a  except the region the bail  11  and the actuator  12  are attached thereto. Moreover, since the resin frame  14  is plated with metal, multi-layered nickel (Ni) and gold (Au), in entire surface thereof, the frame  14  may be grounded by the fingers,  13   a  and  13   b , coming in contact to the cage. 
   The tip of the finger,  13   a  and  13   b , bends inward, which may escape the transceiver  1  from the positional interference. That is, the optical hub system has been developed, in which a plurality of transceivers is arranged in high density, with a span substantially equal to the width and the height of the transceiver. When the transceiver is installed in such densely arranged system, i.e., is inserted into or removed from the densely arranged cage, the fingers may disturb the insertion or the extraction of the transceiver, occasionally, the fingers may be broken by hooking the edge of the cage. 
   The finger member  13  of the present transceiver  1  provides a plurality of fingers,  13   a  and  13   b . This ensures the firm electrical contact to achieve the stable shield performance because a plurality contact can be realized for any combination of the finger member  13  and the cage, even when the dispersion in the physical dimension exists. The cage is formed by bending a metal sheet, which may be easily deformed by the insertion and the extraction of the transceiver. For such deformed cage, a plural electrical contact between the finger member  13  and the cage can be realized by providing a plurality of fingers. Moreover, the present finger member  13  is made of stainless sheet with a thickness of around 0.1 mm and is bent to show the resilient characteristic similar to a leaf spring. Accordingly, nearly all fingers can come in contact to the deformed cage. The bend of the fingers,  13   a  and  13   b , is 1 mm or more. 
   The finger member  13  is assembled with the frame  14  to surround the second portion  14   b . That is, referring to  FIGS. 8C and 8D , the flange,  15   b  and  16   b , of the OSA puts the piece  13   f  of the finger member  13  between the partition wall,  14   n  and  14   p , as shown in  FIG. 8C , while other pieces  13   g  bent from the top side  13   e  is inserted into a gap between the heat dissipating member  18  and the frame  14  at the top of the transceiver  1 . Although the heat dissipating member is not illustrated in  FIG. 8B , the member  18  is set to the frame  14  so as to sandwich the piece  13   g  between the frame  14 . By enlarging the slit  13   h , the finger member  13  may be assembled with the frame  14  to surround the second portion  14   b  thereof. The finger member  13  may recover in its original shape shown in  FIGS. 8A and 8B  after the setting by the elasticity intrinsically attributed in the material. Moreover, setting the cover  19  to the frame  14 , the cover  19  wraps the four sides,  13   c  to  13   e , of the finger member  13 , accordingly, the member  13  does not loose. The finger member  13  provides a plurality of projective tabs  13   i  and a plurality of supplemental fingers  13   j  to ensure the firm contact between the cover  19 . 
   The tip of respective fingers,  13   a  and  13   b , extending outward is bent inward. i.e., a portion protruding outward, comes in contact to the inside of the cage. When the transceiver is set within the cage, these fingers,  13   a  and  13   b , are extruding from the edge of the cage. Accordingly, a point between this bent portion and the root of the fingers comes in contact to the edge of the opening of the cage not to the inside of the cage, which avoids the positional interference between the opening formed in the sides of the cage or the latch also formed in the sides thereof to come the cage in electrical contact to the face panel of the host system, which secures the firm and stable contact between the cage and the fingers. Tapping to protrude the center of the fingers,  13   a  and  13   b , outwardly may be applicable to accomplish further stable contact to the cage. The tip of the finger,  13   a  and  13   b , the head portion beyond the bent portion, is set within the hollow  14   z . As illustrated in  FIG. 7B , the bottom of the frame  14  provides two hollows  14   z  in both side portions thereof, while the sides of the first portion  14   a  forms another hollow  14   z  to receiver the tip of the finer  13   a . By setting the tip of the fingers,  13   a  and  13   b , it is prevented for the finger to be peeled off and deformed by accidental force. 
   Assembly of the Bail and the Actuator 
   The releasing mechanism for the transceiver  1  of the present invention enables to access the bail  11  not only from the top of the transceiver  1  but also from the bottom thereof. That is, by setting the releasing position of the bail  11  to the center of the optical receptacle, while the latching position not only to the top but also to the bottom of the receptacle, it is achieved to operate the bail in ease even when the transceiver  1  is set in the densely arranged cage. 
   However, in the case that both the top and bottom positions correspond to the latching position with the rotational center of the bail  11  being in the middle of the receptacle as shown in  FIG. 9B , which corresponds to the releasing position, the room protruding in the front of the receptacle to grip the bail  11  is compelled to narrow compared to the case that the latching position is set only in the top or the bottom by setting the rotational center of the bail  11  close to the bottom or the center of the receptacle, as shown in  FIG. 9A , which causes a troublesome action when the transceiver  1  is released from the cage. Although the lengthened bail  11  expands the room to grip the bail when the rotational axis is set in the middle of the receptacle, this also expands the movable range of the bail  11 , which accordingly reduces the installation density. Moreover, the agreement that rules the outer dimension of the transceiver  1  defines that the length protruding from the cover in the vertical direction is smaller than 2 mm. 
   On the other hand, to set the center of the rotation close to the edge of the receptacle may widen the room to grip the bail  11 . However, due to the specification of the optical plug to be inserted in to the optical receptacle, the center of the rotation is necessary to be formed apart from the edge of the receptacle. Thus, the room to grip the bail  11  is ensured only 2.5 mm by the configuration to assume both the top and the bottom to be the latching position shown in  FIG. 9A  compared to the case that only the top is the latching position shown in  FIG. 9B , which ensures the room  1  to grip the bail  11  substantially 6 mm. 
     FIG. 10  is a schematic diagram explaining the present mechanism of the bail  11 . The bail  11  sets three positions, A, B, and C, corresponding to the top, the center and the bottom of the receptacle, respectively. The bail  11  provides two guide projections, “a” and “o”, respectively. The former projection “a” may slide along the groove R, while the latter projection “o” may slide along the groove S. The groove R constitutes, in the present embodiment, a portion of the arc with the center “O” positioning on the virtual line extending the groove S outward. 
   Specifically, when the bail  11  is in the position A, in the top of the transceiver  1 , the guide projection “a” is set in the bottom of the groove R, while the other guide projection “o” is set in the rear end of the groove S. Rotating the bail  11  to the position B, in the front of the receptacle, the guide projection “a” slides within the groove R to the rear end “a′”, while the other projection “o” slides within the groove S to the front end “o′”. Comparing the case that the bail  11  rotates around the guide projection “o”, the bail  11  extrudes from the front of the receptacle by the length the guide projection “o” sliding within the groove S. Further rotating the bail  11  to the bottom position C of the receptacle, the guide projection “a” positions in the top within the groove R, while the other guide projection “o” positions in the rear end within the groove S again. The positions A and B make a symmetrical relation. 
   In the present mechanism of the bail  11 , both the top and the bottom of the receptacle provide the latching position. Besides, the bail  11  protrudes from the front of the receptacle by the length m, which corresponds to the length the second guide projection “o” slides within the groove S and is greater than the case that the bail  11  rotates around the static projection “o”. Accordingly, even when the cage is densely arranged in the host system, the bail  11  may be handled in ease. 
   The description above as referring to  FIG. 10  is based on the arched groove R. However, the liner groove R, which makes a T-shaped configuration with the groove S, may show the same function as the description above. When the linear groove R continues to the other linear groove S, the bail  11  would be movable in up and down at the latching positions A and C. When the linear groove R is apart from the linear groove S at the neck position, the rattle motion at the latching positions, A and C, can be prevented but the bail  11  can not stand in vertical to the receptacle. As long as two grooves, R and S, are isolated to each other and the initial position for the first guide projection “a” makes a vertical position against to the initial position for the second guide projection “o”, the configuration of the groove R is not restricted to an arched shape. 
     FIGS. 11 to 13  correspond to the positions, A to C, of the bail  11  in  FIG. 10 , respectively, and each shows the appearance of the bail  11 , the actuator  12 , and the front portion of the frame  14 . Next, the releasing mechanism of the present transceiver  1  will be explained as referring to drawings from  FIG. 11A  to  FIG. 13B . 
     FIG. 11A  is a perspective view showing the bail  11  in the top latching position A, while  FIG. 11B  is a side view thereof. In these drawings, one of the receptacles  1   a  receives an optical connector  2 . The bail  11  comprises a pair of leg portions  11   b  and a grip  11   a  connecting the leg portions  11   b , and the bail  11  has a U-shaped configuration. The bail  11  may be made of metal or resin. The present transceiver  1  provides the bail  11  formed by the metal die-casting. On a center of the leg portion  11   b  is provided with a cam  11   d  and the first guide projection  11   e  stacked on the cam  11   d  with a center thereof identical to each other, while the tip portion of the leg  11   b  forms the second guide projection  11   c  so as to face the projection in the other leg  11   b . On the outer side wall of the first portion  14   a  of the frame  14  is formed with the sliding groove  14   j , which corresponds to the linear groove S in  FIG. 10 , to receive the first guide projection  11   e  and the second sliding groove  14   i , corresponding to the arched groove R in  FIG. 10 , to receive the second guide projection  11   c . The bail  11  may rotate in the front of the receptacle as respective guide projections,  11   c  and  11   e , slide within two grooves,  14   j  and  14   i , respectively. 
   The actuator  12 , assembled with the frame  14  by fitting the center  12   b  thereof into the hooked projection  14   r , comprises two arm portions,  12   e  and  12   d , putting the center  12   b  therebetween. On the tip of the rear arm  12   e  is formed with a latching projection  12   a  that engages with the cage, while the front arm  12   d  provides a sliding surface  12   c . The entire actuator  12  is supported from the downward by the support fin  19   b  of the cover  19  that extends from the front end. When the bail  11  is in the top latching position A, the minor surface of the cam  11   d , which is attributed to a minor axis, comes in contact to the sliding surface  12   c . In this position, since the front arm  12   d  is always pushed up by the support fin  19   b , the sliding surface  12   c  is in the highest position, while the latching projection  12   a  in the other end of the actuator  12  is in the lowest position, protruding outward in the maximum, to engage with the cage. 
   Rotating the bail  11  to the releasing position B, in the front of the receptacle,  FIG. 12A  shows a perspective view, while  FIG. 12B  shows a side view of the relation between the bail  11  and the actuator  12 , in this releasing position. The first guide projection  11   e  slides within the first groove  14   j  to the front end thereof, while the second guide projection  11   c  moves to the middle of the second sliding groove  14   i . Accordingly, the grip  11   a  of the bail  11  further protrudes by this sliding length of the first guiding projection  11   e , which enables to handle the grip  11   a  in ease even in the densely arranged cages. 
   In this position, the cam  11   d  comes in contact to the sliding surface  12   c  of the actuator  12  in the major surface, which is attributed to a major axis, to push down the actuator  12  in the maximum. Accordingly, the latching projection  12   a  formed in the tip of the rear arm  12   e  is pulled inward to the frame  14  to release the engagement of the projection  12   a  with the cage. 
   Further rotating the bail  11  to the bottom latching position C, which is shown in  FIG. 13A  in a perspective view and  FIG. 13B  in a plan view, the first guide projection  11   e  slides to the rear end of the first sliding groove  14   j  while the second guide projection  11   c  slides to the topmost within the second guiding groove  14   i . Moreover, the minor surface of the cam  11   d  comes in contact to the sliding surface  12   c , accordingly, the latching projection  12   a  protrudes outward in the maximum to engage with the cage. 
   During the rotation of the bail  11 , the actuator  12  is supported from the downward by the support fin  19   b  such that the actuator  12  is not disassembled with the frame  14 . On the other hand, for the front and back motion of the actuator  12 , the hooked projection  14   r  restricts the backward motion while the projection  14   o  formed in the front side of the frame  14  restricts the frontward motion of the actuator  12 . Accordingly, only the seesaw motion is allowed for the actuator  12  once set in the predetermined position. 
     FIG. 14  views the transceiver  1  inserted within the cage  3  from the bottom. The cage  3 , configured to a metal box with one end thereof opened for the outside, receives the transceiver  1  in this open end, and only the bail  11  and the actuator  12  are exposed from the cage  3 . The cage  3  provides a plurality of stud pins  3   c  to fix the cage  3  on the host system. Moreover, in the peripheral of the open end of the cage  3  is formed with a plurality of ground tabs  3   a , which comes in contact to the edge of the opening of the face panel, into which the transceiver is inserted. When the transceiver is removed from the cage  3 , this ground tabs suppress the EMI noise generated within the host system to leak from the opening or the propagating radiation in the outside to jump into the host system. 
   On the bottom of the cage  3  is provided with an opening  3   d  configured in a triangle, with which the latching projection  12   a  of the actuator engages to latch the transceiver  1  with the cage  3 . To rotate the bail  11  to pull up the latching projection  12   a  may disengage the latching projection  12   a  with the opening  3   d  to release the transceiver  1  from the cage  3 . 
   Assembly of the Cover 
   The cover  19 , as shown in  FIGS. 1A and 1B , covers the heat dissipating member  18  only in the both sides thereof to expose the most of the top surface. The cover  19  is set to the transceiver  1  from the rear thereof so as to put the frame  14 , the substrate  17  and the heat dissipating member  18  within the cover. By fitting the opening formed in the latch tab  19   a  with the projection  14   g  in both sides of the first portion  14   a  of the frame  14 , the cover  19  may be assembled with the frame  14 , the substrate  17 , and the heat dissipating member  18 . In this process, the latching projection  12   a  of the actuator  12  protrudes through the opening  19   c  in the root of the support fin  19   b  provided in the front tip of the cover  19 , which does not disturb the latching mechanism between the latching projection  12   a  and the opening  3   d  in the cage  3 . In the both sides of the cover  19  are formed with a dent  19   d  to enhance the thermal coupling between the heat dissipating member  18  and the cover  19 . That is, as shown in a cross section of  FIG. 15 , the distance between the dents  19   d  is set slightly smaller than the width of the heat dissipating member  18  to make the member  18  in firmly and stably contact to the cover  19  in the transverse direction.  FIG. 15  is a cross section taken along the line A-A in  FIG. 1A . 
   Moreover, the cover  19  provides a piece  19   e  bent inward in both sides thereof, by which the heat dissipating member  18 , the frame  14  and the substrate  17  is put between the top surface of the cover  19 . By setting the gap from this bent portion to the top of the cover  19  slightly smaller than the total thickness of these three members,  14 ,  17  and  18 , the cover  19  firmly sets these members between the bent portion  19   e  and the top without any rattling. The thickness of the thermal sheet  20  is so selected that the summed thickness of the thermal sheet  20  and the IC  20   c  is greater by 30% than the height of the frame  14 . That is, the thermal sheet  20  is always compressed by 30% to couple the sheet  20  with the IC  20   c  in thermally stable. The cover  19 , as already explained, may play a role to fix the finger member  13  by putting the member  13  with the frame  14 . 
   Thus described transceiver  1  of the present invention, in particular, the releasing mechanism of the bail  11  combined with the actuator  12  and the cover  19  may solve a subject that, when the cages are densely installed in the optical hub system, the target transceiver in the cage is hard to access because the cages neighbor to the target transceiver and the optical connector and the optical cables accompanied with the transceiver received in the neighbor faces. Because the bail of the present transceiver may widen the room from the front of the receptacle by dynamically protruding therefrom and may be stable in both the bottom and the top of the receptacle, it is able to grip the bail even in the densely arranged cage.