Abstract:
A mounting for a computer accessory such as a hard disc drive comprises a tray ( 2 ) for accommodating the accessory ( 1 ) which can be inserted into a mounting bay in the computer against the bias of a pair of springs ( 4 ). The tray ( 2 ) carries a bezel member ( 7 ) movable along the insertion path independently of the tray to latch or unlatch the tray in place, using latching members ( 6 ) in association with latching tracks formed in the bezel, by way of a push-push action.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to digital computers and particularly to the mounting of accessories in such computers and like systems. 
     BACKGROUND OF THE INVENTION 
     Conventionally digital computers and particularly the class of digital computers referred to as personal computers (PC&#39;s) are supplied with mounting bays to accommodate accessories such as disc storage devices which may be added after initial installation of the computer. Typically the accessory is electrically connected to the system by a multi-way electrical connector and the mounting bay includes securing brackets to hold the accessory in place using nuts and bolts or other fasteners. Typically the mounting bay is located at the front of the machine and a bezel is provided to cover the front of the accessory to enhance the appearance of the installation and where required to provide access for discs or other media. 
     Such accessories when installed have normally become virtually permanent features of the computer, with very little need for subsequent removal. However for certain applications it is desirable that the accessory be readily removable and replaceable, for example where it is required to transport a hard disc drive to another installation or to remove it for security reasons. Existing accessory mountings are not well suited to such applications and it is an object of the present invention to provide a mounting which permits easy removal and replacement. 
     SUMMARY OF THE INVENTION 
     According to the invention there is provided an accessory mounting for a digital computer or the like comprising an accessory tray for accommodating an accessory and adapted for insertion into a mounting bay of said computer along an insertion path against resilient means arranged to bias said tray out of said mounting bay when fully inserted and latching means adapted to hold said tray in said mounting bay against the bias of said resilient means and operable to release said accessory for ejection from said mounting bay by said bias. 
     In embodiments of the invention described below a bezel member is mounted on the tray for movement relative thereto in the direction of the insertion path and the latching means includes a track member carried by the bezel member and adapted to co-operate with a follower to cause the tray to be latched in a fully inserted position or to be released from such position in response to movement of the bezel member relative to the tray in the direction of insertion. Bias means are provided to bias the bezel member away from the tray with a force weaker than that exerted by the resilient means, whereby pressure applied to the bezel member causes movement thereof relative to the tray to effect latching of the tray when unlatched and release of the tray when latched. 
     In a first embodiment of the invention the tray carries a rear mounted ejection spring which provides the outward bias by bearing against the rear of the mounting bay when the accessory is pushed into place. The bezel member includes a pair of tracks substantially cardioid in shape, one moulded in each side thereof. The bottom of the track is stepped to ensure that a follower pin mounted on a flexible arm secured to the mounting bay proceeds around the track in one direction only. 
     In a second embodiment of the invention the tray is arranged to engage springs mounted on the rear of the mounting bay and the bezel is movable relative to the tray to cause a pair of latches one on each side of the tray to be lowered and raised, co-operating with pins secured to the accessory housing respectively to retain and release the accessory. In this embodiment a track element located centrally of the bezel provides the raising and lowering movement of the latches by cam action on a follower mounted on an axle which carries the latches. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the invention may be well understood the embodiments referred to above will now be described with reference to the accompanying drawings in which: 
     FIG. 1 is a perspective view of the first embodiment showing the mounting in position in the computer. 
     FIG. 2 shows the latching tracks on either side of the bezel in the embodiment of FIG.  1 . 
     FIG. 2 a  is a view of the end of a latching track. 
     FIG. 3 is an exploded view of the tray and its associated bezel. 
     FIG. 4 shows a typical installation in a multi-accessory environment. 
     FIG. 5 is a general view of the second embodiment of the invention together with the associated accessory cage. 
     FIG. 6 is an exploded view of the embodiment of FIG.  5 . 
     FIGS. 7 a - 7   e  show parts of the mechanism of the embodiment of FIG. 5 in greater detail. 
     FIGS. 8-14 show the mechanism of the embodiment of FIG. 5 at various stages in its operation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1 there is shown a mounting for a hard disc file  1  comprising a tray  2  provided with guide grooves  3  on either side which co-operate with guide rails (not shown) in the computer&#39;s accessory housing to guide the tray into position. A pair of springs  4  are provided to bias the tray outwardly of the housing when pushed fully home. At either side of the housing and secured thereto is a latch bar support  5  each supporting a latch bar  6  which extends forward through the corresponding groove  3  and carries at its end a follower pin (not shown). A separate bezel  7  has end pieces  8  which are mounted to retain the corresponding latch bar and follower pin in a latching track formed in the side of the bezel  7  as will be described with reference to FIG.  2 . 
     FIG. 2 shows the bezel  7  with the end pieces  8  displaced to show the manner in which the latching bar  6  and its associated follower pin  9  engage a substantially cardioid-shaped latching track  10 . As shown in FIG. 2 a  the track  10  is stepped at  10   a ,  10   b ,  10   c  and  10   d  and provided with inclined sections between the steps to permit the pin  9  to travel therearound in one direction only, and is provided with a port  10 e at the cusp of the cardioid to permit entry and exit of the follower pin  9 . 
     FIG. 3 shows the manner in which the bezel  7  is mounted on the tray  2 . Each of a pair of support pins  11  is snapped through a matching hole in the bezel  7  and co-operates with an associated compression spring  12  to bias the bezel away from the tray  2 . A typical installation is shown in FIG.  4  and takes the form of a housing cage  13  adapted to accommodate up to six accessories providing, for each accessory, a connector  14 , guide rails  15 , latching bars  17  and associated latching bar supports  18 . 
     In operation, when a tray  2  carrying an accessory is inserted into the computer housing  13  the guide grooves  3  in the tray engage the corresponding guide rails  15  and the tray is pushed into place by applying force to the front bezel. This compresses the springs  12  which normally keep the bezel and tray apart until the bezel contacts the tray. The force applied to the bezel is then transmitted to the tray, which moves into the housing towards the corresponding connector  14  and the associated springs  4  start to compress. 
     Shortly before the tray is fully home the tracking pins  9  enter the latching tracks  10  in the bezel. Each pin follows the cardioid shape of the associated track, the base of which, as already described, is stepped to prevent return of the pin to its entry point. The latching bars  17  are designed to flex in a horizontal direction as their associated tracking pins ride up the inclined sections of the tracks and over the steps  10   a -d , the restoring force under flexure retaining the pin in the track. The pin drops over the step  10   a  in the track and, on release of the bezel, enters the cleft of the cardioid over step  10   b  thereby locking the tray in the inserted position. 
     In order to remove the drive the bezel is depressed again. This drives the pin into the other half of the cardioid where it drops over a step  10   c  preventing its return to the locked position. At this point no further compression of the springs  12  can take place. The operator can then release all pressure on the bezel which permits the tray to eject itself partially from the housing under the effect of the compressed springs  4 . The bezel returns to its free position and the tracking pins  9  leave the tracks  10 . The tray can then be fully withdrawn from the housing. 
     The second embodiment of the invention is shown in FIGS. 5-13. 
     Referring first to FIG. 5 a computer housing  18  providing accommodation for up to three accessories is shown. Connectors  19  are provided as before together with guide rails  20 . However in this embodiment the housing itself provides the resilient bias for an accessory tray accommodated in the housing by means of springs  21  mounted on the rear of the housing on either side of the connector  19 . The housing also includes latching pegs  22  which as will be described below are arranged to hold an accessory tray in place when the latter is pushed fully home. 
     The accessory tray  23  is provided as in the previously described embodiment with grooves  24  to define a path along which the tray moves when pushed into the housing. Also mounted in the tray is a latch axle  25  carrying at each end a latching hook  26  which is biased downwards towards the base of the groove  24  by a compression spring  27 . A bezel member  28  is mounted on the tray in a pair of slides  29  so that it can move relative to the tray, in the direction of insertion, against the force of a pair of compression springs  30  which bias the bezel normally outwards with a force less than that exerted by the compression springs  21  in the housing when the tray is pushed home. The latching axle  25  carries a follower  31  which co-operates with a track member  32  which is pivotally mounted in the base of the bezel to lift or lower the follower as the bezel is moved relative to the tray as will be described in detail later. 
     The various components of the embodiment are shown in the exploded view in FIG. 6 from which it will be seen that the track member  32  is mounted for limited rotary movement in a recess  33  in the base of the bezel member  28  against the bias of a torsion spring  34  which normally holds the track member  32  in a clockwise position. The latch axle  25  is seen to carry in addition to the latching hooks  26  and the follower  31  a pair of restraining pins  35  which engage in slots  36  provided in the base of the bezel member  28  to limit movement of the bezel relative to the tray. 
     FIGS. 7 a - 7   e  show the configuration of the track member  32 . As will be seen from FIG. 7 a  the member  32  is mounted in the bezel recess  33  about a pivot point  37  and presents to the A follower pin  31  a series of three linear tracks, tracks  1 ,  2  and  3 , each having an inclined floor, as shown in greater detail in FIGS. 7 b - 7   e . FIG. 7 b  shows the three tracks in plan form, indicating sections taken along the three tracks in FIGS. 7 c, d  and  e  respectively. Thus track  1  (FIG. 7 c ) presents to the follower  31  an incline  37  followed by a step  38  which prevents return of the follower in the reverse direction. Track  2  (FIG. 7 d ) presents a second incline  39  from the step  38  to a plateau position  40  whilst track  3  presents a level transition  41  to a step  42  from which the follower  31  can exit on withdrawal of the tray from the housing. 
     The operation of inserting the tray and bezel will now be described with reference to FIGS. 8-13. FIG. 8 shows part of the tray/bezel assembly prior to entry into the computer housing. The latch axle  25  is biased downwards by the springs  27  and the pins  35  engage the edge of the bezel member  28  to prevent relative movement between the bezel member and the tray. The track member  32  is biased by the torsion spring  34  into its clockwise position. As the tray is inserted into the housing it is guided towards the back of the housing along the rails  20  until the pegs  22  engage the respective latching hooks  26 . As shown in FIG. 9 the latching axle is then rotated by camming action of the pegs  22  on the latching hooks  26  permitting the pins  35  to lift clear of the base of the bezel. 
     Continuing insertion force to the front of the bezel compresses the springs  30  completely and the tray continues to be moved against the compression springs  21  to permit the latch hooks  26  to drop over the pins  22  under the influence of the springs  27 . This allows the latching axle  25  to return to its rest position and the follower  31  to drop into track  1  of the track member  32 , as shown in FIG.  10 . 
     When the insertion force is removed, the tray is retained in the housing by the latch hooks  26  and the pegs  22 , and the bezel member  28  returns to its rest position under the influence of the springs  30 . The follower  31  drops over the step  38  at the end of track  1 . The accessory is now fully latched in position. 
     In order to remove the accessory the bezel is pushed inwards. As shown in FIG. 12 this causes the follower  31  to be driven upwards by the incline in track  2  of the track member  32 , deflecting the latter against the torsion spring  34  and rotating the latching axle  25  to cause the latching hooks  27  to disengage from the pegs  22 . When the follower  31  reaches the end of track  2  it drops over the recess  40  into the third track  3  so that when the force is removed from the bezel the springs  31  are permitted to eject the tray from the housing FIG.  13 . At this point the bezel member  28  moves back to its initial position and the follower  31  runs along track  3  and out of the track member thus returning to its initial starting position. The accessory can then be fully removed from the housing (FIG. 14.) 
     It will be appreciated that various refinements may be made to the embodiments described to improve the performance in particular applications. For example it may be desirable to ensure that the ejection force applied by the springs at the rear of the housing, whether they be built into the tray or the housing be limited to avoid full ejection of the accessory resulting possibly in damage thereto. This could be achieved for example by fitting a rotary damper to the ejection mechanism.