Abstract:
A transceiver module which is easily and conveniently assembled, and which is reliable. The transceiver module comprises a housing, an optoelectronic subassembly, a receptacle, a chassis and a PCB. The optoelectronic subassembly is received in the receptacle. Conductive leads of the optoelectronic subassembly are soldered to the PCB. The chassis is attached to the PCB with screws, and accommodates and protects the PCB. The housing comprises a top housing and a bottom housing. The top housing is attached to the chassis and the receptacle. The top housing and bottom housings are attached together, enclosing therein the receptacle, the chassis and the PCB.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to optoelectronic transceiver modules for fiber-optic communications, and in particular optoelectronic transceiver modules which can be conveniently assembled and which are reliable. 
     2. Description of the Related Art 
     Optoelectronic transceiver modules provide for bi-directional transmission of data between an electrical interface and an optical data link. The module receives electrically encoded data signals which are converted into optical signals and transmitted over the optical data link. Conversely, the module receives optically encoded data signals which are converted into electrical signals and transmitted onto the electrical interface. 
     There is a need for a transceiver module which is highly reliable and durable. A print circuit board (PCB), the most important element of the transceiver module, must be enclosed by a shielding housing which absorbs electromagnetic radiation. This ensures that high frequency signals in the transceiver module do not affect external electrical circuits, and that such signals are not affected by external electromagnetic waves. The PCB must be grounded in order to dissipate any static charges which develop on the PCB. 
     U.S. Pat. No. 5,767,999 discloses a conventional optoelectronic transceiver module. The module comprises a top housing, a bottom housing and a PCB. The PCB is located between the top and the bottom housings. One end of the PCB connects with an electrical connector, and the other end of the PCB connects with optoelectrical components which have leads soldered to the PCB. Unfortunately, the PCB is fixed by plastic positioning dowels. Therefore the housing cannot be effectively connected to a grounding circuit of the PCB. There is no reliable grounding connection between the housing and the PCB. Any static charges on the housing cannot be timely dissipated to ground, which adversely affects the performance of the transceiver module. Furthermore, assembly of this conventional transceiver module is unduly laborious. 
     Another conventional optoelectronic transceiver module is disclosed in U.S. Pat. No. Re. 36,820. A PCB and other optoelectronic components are placed in a rectangular box. By injecting potting material into the box, the PCB and the optoelectronic components can be enclosed. The enclosure of the transceiver module fixes and protects the PCB. However, potting material is expensive and unduly troublesome to use. Furthermore, the structure does not provide satisfactory grounding connection between the PCB and the box. Thus the box does not effectively dissipate buildup of electrostatic charge thereon, and does not provide optimal electromagnetic shielding. 
     In view of the above, there is a need for a transceiver module which can easily and securely fix the PCB in a metal housing while simultaneously effectively establishing a grounding path between the PCB and the metal housing. 
     SUMMARY OF THE INVENTION 
     Therefore, one object of the present invention is to provide a transceiver module which can easily and securely fix a PCB in a housing. 
     Another object of the present invention is to provide a transceiver module with an effective grounding path between a PCB and a housing. 
     The transceiver module of the present invention comprises a housing, an optoelectronic subassembly, a receptacle, a chassis and a PCB. The optoelectronic subassembly is received in the receptacle. Conductive leads of the optoelectronic subassembly are soldered to the PCB. The chassis is attached to the PCB with screws, and accommodates and protects the PCB. The housing comprises a top housing and a bottom housing. The top housing is attached to the chassis and the receptacle. The top housing and the bottom housing are attached together, enclosing therein the receptacle, the chassis and the PCB. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of an optoelectronic transceiver module in accordance with the present invention; 
     FIG. 2 is an exploded perspective view of the optoelectronic transceiver module of FIG. 1, but viewed from another aspect; 
     FIG. 3 is an exploded perspective view of the optoelectronic transceiver module of FIG. 1, but viewed from still another aspect; and 
     FIG. 4 is an assembled view of the optoelectronic transceiver module of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, an optoelectronic transceiver module  99  in accordance with the present invention has a top housing  1 , a bottom housing  2 , a chassis  3 , a receptacle  4 , a PCB  5  and an optoelectronic subassembly  6 . 
     The receptacle  4  has the shape of an oblong box. The receptacle  4  comprises a front portion  43  and a rear portion  44 . The size of the front portion  43  is large than that of the rear portion  44 . Thus a rear face  431  is defined on the front portion  43  around a periphery of a junction of the front and rear portions  43 ,  44 , for abutting a front edge of the top housing  1 . Referring also to FIG. 3, the front portion  43  defines two openings  41 ,  42  though the receptacle  4 . Rear portions of the openings  41 ,  42  are for receiving the optoelectronic subassembly  6 , and front portions of the openings  41 ,  42  are for connecting with an optical connector (not shown) to output optical signals. The optoelectronic subassembly  6  comprises a transceiver. The transceiver comprises a transmitter  61  and a receiver  62 . The transmitter  61  may typically be a laser diode (LD) or light emitting diode (LED), and the receiver  62  may typically be a photo diode. A plurality of conductive leads  605  extends from a rear of the transceiver, and is soldered to the PCB  5 . Two T-shaped grooves  441  are defined in a bottom surface of the rear portion  44  of the receptacle  4 , for engagement of the receptacle  4  with the top housing  1 . A pair of protuberances  442  is formed on a top surface of the receptacle  4 . 
     Referring also to FIG. 2, the PCB  5  has a narrow rear section  52  and a wide front section  51 . Three position holes  511  are defined through the PCB  5  in the vicinity of three edges thereof respectively. The conductive leads  605  of the optoelectronic subassembly  6  are soldered to the front section  51  of the PCB  5 , to establish electrical contact between the optoelectronic subassembly  6  and the PCB  5 . The rear section  52  of the PCB  5  has a row of electrical contacts  520  at a rear end thereof, for electrical connection of the PCB  5  with an electrical connector (not shown). 
     The chassis  3  may be made of metal, plastic or other suitable material. The chassis  3  generally has the shape of an oblong box, for accommodating and protecting the PCB  5 . Three poles  313  depend from a bottom face of the chassis  3 . Three screw holes  312  are defined in a top face of the chassis  3  and through the three poles  313  respectively, corresponding to the three position holes  511  of the PCB  5 . A rear of the chassis  3  forms a seat  33 . A support plate  330  extends forwardly from a bottom of the seat  33 . Two screw holes  311  are defined in the chassis  3 . The chassis  3  has a pair of opposite side walls  32 . Two spaced recesses  320  are defined at a top edge of each side wall  32 , for engagement of the chassis  3  with the bottom housing  2 . A pair of depressions  321  (see FIG. 3) is defined in opposite sides of a rear end of the chassis  3 . Three fastening components, such as screws  8  (only one shown), are for fixing the PCB  5  on the chassis  3 . 
     The bottom housing  2  is made of metal, and has a generally U-shaped configuration. The bottom housing  2  has a rectangular bottom wall  20 , and two side walls  21  extending perpendicularly upwardly from the bottom wall  20 . Two protrusions  212  are inwardly formed at front and rear ends of a top of each side wall  21 , for engaging in the recesses  320  of the chassis  3 . A slot  213  is defined below each protrusion  212  of each side wall  32 . A rectangular opening  211  is defined in each side wall  21  below each slot  213 . The slots  213  and the rectangular openings  211  are for mating with the top housing  1 . 
     The top housing  1  is made of metal, and has a top wall  11 . A shallow trough  110  is formed at a middle of the top wall  1 . Two annular flanges (not labeled) extend downwardly from the trough  110 . Two position holes  111  are respectively defined within the annular flanges, corresponding to the screw holes  311  of the chassis  3 . A pair of parallel grounding tabs  113  is formed near a front end of the top wall  11  of the top housing  1 . A pair of parallel rectangular openings  112  is defined between the grounding tabs  113  and the trough  110 , corresponding to the protuberances  442  of the receptacle  4 . A pair of forward side walls  14  depends from opposite sides of the top wall  11  of the top housing  1 . A pair of rearward side walls  12  depends from opposite sides of the top wall  11  of the top housing  1 . Two pairs of locking tabs  13  respectively depend from opposite sides of the top wall  11  of the top housing  1 , between the forward and rearward side walls  14 ,  12 . A T-shaped flap  142  is inwardly formed at a bottom of each forward side wall  14 , for engaging in the T-shaped grooves  441  of the receptacle  4 . Each forward side wall  14  has a grounding tab  113 . A tab  121  (best seen in FIG. 3) extends inwardly from a rear end of each rearward side wall  12 , for engaging in the depressions  321  of the chassis  3 . Each locking tab  13  is a rectangular plate, the size of which corresponds to each slot  213  of the bottom housing  2 . A spring tongue  131  is outwardly formed at a center of each locking tab  13 . A lower end of each spring tongue  131  is integrally joined with the locking tab  13 , and an upper end of each spring tongue  131  protrudes outwardly from the locking tab  13 . Two fastening components, such as screws  7 , are for attaching the top housing  1  to the chassis  3 . 
     Referring to FIG. 4, a labeling tape  991  is for attachment to the optoelectronic transceiver module  99  after assembly. 
     In assembly of the optoelectronic transceiver module  99 , the PCB  5  and the chassis  3  are firstly attached together. The rear section  52  of the PCB  5  is inserted into the seat  33  of the chassis  3 . The poles  313  of the chassis  3  press down on the PCB  5 , and the support plate  330  of the chassis  3  supports the PCB  5  by abutting against a bottom face thereof. The screws  8  are extended through the position holes  511  of the PCB  5  to threadedly engage in the screw holes  312  of the poles  313 . The top housing  1  is then attached to the receptacle  4  and the chassis  3 . The screws  7  are extended through the position holes  111  of the top housing  1  to threadedly engage in the screw holes  311  of the chassis  3 . The protuberances  442  of the receptacle  4  are received in the openings  112  of the top housing  1 . The T-shaped flaps  142  of the top housing  1  are engaged in the T-shaped grooves  441  of the receptacle  4 . Finally, the bottom housing  2  is attached to the chassis  3  and the top housing  1 . The locking tabs  13  of the top housing  1  are extended through the slots  213  of the bottom housing  2  until the spring tongues  131  of the locking tabs  13  engage in the openings  211  of the bottom housing  2 . The protrusions  212  of the bottom housing  2  are engaged in the recesses  320  of the chassis  3 . FIG. 4 shows the finally assembled optoelectronic transceiver module  99 . The labeling tape  991  is glued to the trough  110  of the top housing  1 , to show some information about the optoelectronic transceiver module  99  and to cover the screws  7 . 
     The chassis  3  of the optoelectronic transceiver module  99  is preferably made of metal. The PCB  5  at the position holes  511  is coated with conductive material, and the conductive material is connected with a grounding circuit of the PCB  5 . The chassis  3  is thus electrically connected with the grounding circuit of the PCB  5  via the screws  8  which engage with the conductive coating at the position holes  511 . The top and bottom housings  1 ,  2  electrically contact with the chassis  3 . The optoelectronic transceiver module  9  thus effectively forms a grounding path between the grounding circuit of the PCB  5  and the top and bottom housings  1 ,  2 . Thus any static charge which develops on the top or bottom housings  1 ,  2  is effectively dissipated. 
     It should be understood that various changes and modifications to the presently preferred embodiment described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing the present invention&#39;s advantages. Thus, it is intended that such changes and modifications be covered by the appended claims.