Transceiver guide rail with heat sink guide

[0001] The present invention claims priority from U.S. patent application Ser. No. 60/518,815 filed Nov. 10, 2003, which is incorporated herein by reference.

[0002] The present invention relates to a guide rail for an optical transceiver device, and in particular to a guide rail with a guide for ensuring that the heat sink fins extending from the optical transceiver housing are not damaged during insertion.

[0003] Traditionally, pluggable small form factor optical transceivers have been supported on a host circuit board utilizing a cage 1, see FIG. 1, such as the one disclosed in U.S. Pat. No. 6,419,523 issued Jul. 16, 2002 to Hon Hai Precision Ind. Co., which completely surrounds the transceiver module except for a few holes 2 in the top 3, providing good EMI protection. Unfortunately, the amount of heat dissipation is greatly reduced, as air flow over the transceiver module is limited. Moreover, since the transceiver module is completely enclosed, no additional thermally conductive surfaces can be mounted thereto for added heat dissipation.

[0004] With reference to FIG. 2, with the advent of 10 Gb/s optical transceivers 11, which require heat sinks 12, including large heat-sinking pins or fins 12a extending therefrom, for dissipating the large amounts of heat generated therein, open top guide rails 13, have become a more logical choice of support for a host circuit board 15. Unfortunately, during insertion into the guide rail 13, the large fins 12a occasionally contact an edge of an opening in a faceplate 14, causing a ratcheting series of impacts, which can damage the fins 12a, i.e. hamper their ability to dissipate heat.

[0005] An object of the present invention is to overcome the shortcomings of the prior art by providing a transceiver guide rail with a guide for facilitating insertion of a transceiver into the guide rail without damaging the heat sink fins extending therefrom.

[0006] Accordingly, the present invention relates to a guide rail for mounting an optical transceiver, which has a heat sink extending therefrom, onto a host circuit board of a host device, which has a faceplate with an opening for receiving the optical transceiver, comprising:

[0007] a first side, a second side and a rear frame member for receiving the optical transceiver and guiding the transceiver into position on the host circuit board;

[0008] a first arm extending from the first side proximate the opening above the heat sink and below an edge of the opening for guiding the optical transceiver into position, thereby preventing contact between the heat sink and the faceplate.

[0014] With reference to FIGS. 3 and 4, a guide rail 21, according to the present invention, includes a metallic frame with a left side 22, a right side 23 and a rear section 24. Each of the left and right sides 22 and 23, respectively, includes an opening 26 at a front end thereof for receiving a latching member 27 extending from the transceiver 11, as detailed in co-pending U.S. patent application Ser. No. 2003/0236019, which is incorporated herein by reference. Alignment tabs 28 are bent from each of the left and right sides 22 and 23, respectively, for engaging the undersurface of the heat sink 12, thereby guiding the transceiver module 11 into position. A shroud 29 extends from the rear section 24 for covering an electrical connector (not show), which connects the transceiver module 11 to the host circuit board 15.

[0015] L-shaped arms 31, which extend upwardly from proximate the ends of the left and right sides 22 and 23, respectively, include a planar vertical section 32 extending above the height of the heat sink fins 12a, a planar horizontal section 33 extending perpendicular to the vertical section 32 over top of the heat sink fins 12a, and a bent lead-in section 34 extending outwardly and upwardly from the horizontal section 33. The lead-in section 34 extends upwardly at an acute angle, e.g. 45°, from the horizontal section 33, i.e. at an acute angle to the direction of insertion of the module 11 into the rail 21. During insertion, the lead-in section 34 provides a camming surface for guiding the top of the heat sink fins 12a underneath of the horizontal section 33, which is wide enough, e.g. the spacing of three or four heat sink fins 12a, to prevent the heat sink fins 12a from ratcheting thereon. The inner end of the lead-in section 34 is positioned below the edge of the opening in the faceplate 14, whereby the lead-in section guides the heat sink fins away from the faceplate 14 during insertion. Preferably, the outer free end of the lead-in section 34 is also positioned below the edge of the opening in the faceplate 14 to ensure that the heat sink fins 12a do not contact the faceplate 14 during insertion. Preferably, the arms 31 are contiguous with the guide rail 21, and made of a resilient metal enabling the arms 31 to bend during insertion, but ensuring that they provide a spring biasing force pushing the transceiver 11 down into position.

[0016] FIG. 4 illustrates a second embodiment of the present invention in which the vertical section 42 is extendable to various vertical positions to accommodate heat sink fins 12a with different heights. The vertical section 42 comprises a first base portion 43 extending from the guide rail 23 and a second moveable portion 44, slideable relative to the first base portion 43. Tabs 46 extending from the sides of the second moveable portion 44 enable the second moveable portion 44 to be adjusted and then locked into a desired position. Other means for locking the second moveable portion 44 in position are possible, in particular, if the different heat sink fin heights are known, the vertical section 42 could have predetermined notches 47 for receiving the tabs 46 or some other projection extending from the second moveable portion 44.