Abstract:
A telecommunications server comprises a switch/larch mechanism for use in online removal or insertion of a peripheral card, such as a PCI card. A bulkhead is adapted for mating engagement with a bulkhead mounting bracket of the peripheral card when the peripheral card is installed in the switch/latch mechanism. A doorbell switch having a vertical range of motion is manually depressed to signal the server and commence an orderly shutdown of the peripheral card in advance of online replacement of the peripheral card. A panel switch provides a mechanical lock retaining the peripheral card in place, and also function as a backup power interrupt device to protect the peripheral card in the event that depression of the doorbell button does not result in an orderly shutdown of the peripheral card.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention pertains to the field of switch mechanisms that facilitate online replacement of printed circuit board cards, such as peripheral component interface (PCI) cards. The switch mechanisms also function as a mechanical latch. 
     2. Discussion of the Related Art 
     Computer system maintenance, repair and upgrade operations frequently involve the insertion or replacement of expansion cards. For example, an expansion card that provides a specific functionality may be inserted into a PCI or ISA bus. This card may be replaced for a variety of reasons including system upgrades or failure of the card. 
     Standard operating procedures for the insertion or replacement of expansion cards have traditionally required the computer system to be shut-down or powered off during the insertion or replacement procedures. This requirement is problematic because the computer system is unavailable to fulfill its intended function during the procedure. The system unavailability is not necessarily a problem is some cases, however, unavailability causes severe disruptions in other cases. For example, in the case of a telecommunications server that supports a large number of clients, even temporary unavailability of the server may cause extreme inconvenience to the client base. 
     One solution to the problem of having to shut down computer systems for maintenance is to provide an online or hot-swapping capability that permits the insertion and removal of expansion cards while the system is operational. For example, U.S. Pat. No. 5,568,610 teaches the use of capacitive plates coupled to corresponding variable frequency oscillators that, in combination, detect the insertion or removal of an expansion card. U.S. Pat. No. 6,252,514 describes a sliding lock assembly coupled with a detector that is capable of notifying the system when the lock assembly is engaged or disengaged, in order to prepare the system for selective insertion or removal of an expansion card. Similarly, U.S. Pat. No. 6,247,080 describes a method of hot-swapping peripheral adapters 
     A current industry trend is to provide two switches for the hot-swapping or online replacement of PCI cards. A first switch is known as a “doorbell” switch that an operator manually depresses to notify the system that the card is to be removed. The system, as needed, then saves states and commences an orderly shutdown of either the individual card. A second switch is used to unlatch the card from its location inside the chassis and, if the card is still under power at the time of unlatching, sends a signal that require the system to shut off power to the card before electrical damage can occur to the card. 
     While mechanisms and methods for the hot-swapping of expansion cards or peripheral adapters are known in the art, various problems arise in connection with the use of known mechanisms. For example, mechanisms that require the provision of a hole in a computer chassis or housing also produce a corresponding electromagnetic interference leak emanating from the hole. Furthermore, the layout of the switches and latching mechanisms is often ergonomically inconvenient. 
     There remains a need to provide an ergonomically improved switch and latch mechanism for use in online replacement of PCI cards and other expansion cards, that does not require openings which result in an EMI leak, and occupies only a small footprint. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the problems that are outlined above by providing an improved switch/latch mechanism which presents itself for easy viewing during use during online replacement of PCI cards and other expansion cards, does not require openings which result in an EMI leak, and occupies a small footprint. 
     The switch/latch mechanism according to the various embodiments and instrumentalities described herein retains a generally planar printed circuit board having a forward end, a rearward end, and an L-shaped bulkhead mounting bracket. The L-shaped mounting bracket has a first bracket segment that is connected to the forward end of the printed circuit board, and a second bracket segment extending forward of the first segment. 
     In an embodiment that is further described below, the switch/latch mechanism comprises a bulkhead adapted for mating engagement with the bulkhead mounting bracket of the peripheral card when the peripheral card is installed in the switch/latch mechanism. The bulkhead includes a first bulkhead wall that is oriented in parallel to the first bracket segment, and a second bulkhead wall that is oriented in parallel to the second bracket segment when the peripheral card is installed in the switch/latch mechanism. The second bulkhead wall includes an alignment pin for use in positioning the second bracket segment on the second bulkhead wall. A switch housing is deployed on a forward end of the second bulkhead wall. The switch housing includes a first switch wall parallel to the first bulkhead wall, and a second switch wall parallel to the second bulkhead wall. A paddle switch is mounted on the switch housing through use of a hinge axis that permits the paddle switch to travel in an arcuate path of motion over the second bulkhead wall. The hinge axis oriented in parallel to the first switch wall, so that the arcuate path of motion extends between a locked position of normal operation engaging the alignment pin, and an interrupt position remote from the alignment pin. A doorbell switch is mounted in the second switch wall and has a range of motion perpendicular to the second switch wall between an extended position of normal use and a compressed position. 
     In particularly preferred embodiments, the paddle switch includes a flag arm and a first optical switch component internal to the switch housing. The first optical switch component has a first slot permitting passage of the flag arm for optical interrupt purposes when the paddle switch is in one of the locked position of normal operation engaging the alignment pin and the interrupt position remote from the alignment pin. The paddle switch may include a snap mechanism for engaging the alignment pin when the panel switch is placed in the locked position of normal operation. 
     The doorbell switch has an interrupt arm and a second optical switch component internal to the switch housing. The second optical switch component has a second slot permitting passage of the interrupt arm for optical interrupt purposes when the doorbell switch is in one of the extended position of normal use and the compressed position. The doorbell switch may also comprise an integrally formed spring biasing the doorbell switch into the extended position of normal use. 
     The first slot and the second slot may be placed in transverse orientation with respect to one another, to provide an extremely compact assembly that occupies a very small footprint. The compact assembly permits the system chassis to occupy a lower vertical profile or, for example, the same profile may now contain an air venting structure, such as a perforated wall rising above the switch housing. 
     The switch/latch mechanism preferably includes a plurality of paddle switch and doorbell switch pairs attached to the switch housing. Each pair is allocated to a corresponding peripheral bus. 
     The switch housing may be advantageously formed using a modular construction comprising successive units each capable of housing a portion of the plurality of paddle switch and doorbell switch pairs. The successive units may, for example, comprise clip latch structure for engaging the second bulkhead wall to retain the successive units in fixed location with respect to one another. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top, rear perspective view showing a telecommunications server that incorporates a switch/latch mechanism according to the instrumentalities described herein; 
     FIG. 2 is a top, rear perspective view providing additional detail with respect to the switch/latch mechanism; 
     FIG. 3 is a rear perspective view showing a switch housing component and a printed circuit board for use in the switch/latch mechanism; 
     FIG. 4 is a bottom, rear perspective view of the printed circuit board showing a deployment of two optical switch components in transverse orientation to one another; 
     FIG. 5 is a bottom, front perspective view of the switch housing component showing partial installation of a doorbell switch component; and 
     FIG. 6 is a bottom side perspective view of a paddle switch body. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIG. 1 depicts a telecommunications server  100  that resides in a chassis  102 . The top portion of chassis  102  has been removed to reveal internal components, such as a motherboard  104  that contains a processor  106 , RAM banks  108  and  110 , a power supply  112 , and a drive bay  114  that may house, for example, a CD-ROM drive  115 , as well as other storage media, such as a hard drive (not shown). The components that have been described thus far are conventional components, and are only shown to describe, in a general sense, an intended environment of use for a bank  116  of switch/latch mechanisms, such as switch/latch mechanisms  118  and  120 . Apart from the bank  116 , the telecommunications server  100  could be any other conventional electronic system, such as a network server, personal computer, or laboratory test instrumentation that utilizes expansion cards or peripheral cards, such as cards  122  and  124 . Each of these peripheral cards may, for example, be allocated to a telecommunications channel. 
     Each of the switch/latch mechanisms, such as such as switch/latch mechanisms  118  and  120 , are allocated to a corresponding bus. For example, as shown in FIG. 1, a switch/latch mechanism  126  is allocated to a bus  128 , which may be any type of bus but is preferably a PCI bus. As shown in FIG. 1, bus  128  does not contain a peripheral card, and a sheet metal blank  130  seals an opening in bulkhead  132  of the type that permits access to a peripheral card that may be installed in bus  128 . The switch/latch mechanisms  118  and  120  each include a pair of switches comprising a doorbell switch and a paddle switch team. For example, one such team comprising switch/latch mechanism  120  includes a doorbell switch  134  and a paddle switch  136 , which are allocated to peripheral card  124 . A switch housing  138  supports a doorbell switch array  140  and a paddle switch array  142 . An interface cable  144  connects the doorbell switch array  140  and the paddle switch array  142  to the motherboard  104  for the transmission of operation control signals. 
     Operation of the telecommunication server  100  permits online replacement or “hot-swapping” of peripheral cards. Protocols for online replacement of peripheral cards are programmed into conventional device manageability control software and firmware. For example, an operator intending to replace peripheral card  124  may depress doorbell switch  134 , which sends a signal to the telecommunications server  100  requiring a save of operational states in peripheral card  124 , as well as a graceful shutdown of the functions being performed by peripheral card  124 . The telecommunications server  100  also switches to interrupt system power servicing peripheral card  124  to complete the graceful shutdown procedure. Paddle switch  136  is a mechanical interlock that selectively retains peripheral card  124  in a fixed position or may be opened to permit removal of the peripheral card  124 . Opening of paddle switch  136  also provides an immediate power interrupt that disrupts the operation of peripheral card  124  without a graceful shutdown if depression of the doorbell switch  134  has not disrupted power to peripheral card  124 . Disruption of power to peripheral card  124  is required to avoid electronic damage, otherwise, arising from power continuity during online replacement. 
     With power to peripheral card  124  disrupted, the operator is free to remove peripheral card  124  and, optionally, replace peripheral card  124  with another peripheral card. Subsequent closure of the paddle switch  136  followed by depression of the doorbell switch  134  permits the telecommunications server  100  to use the new peripheral card in place of peripheral card  124 , e.g., by restoring the saved states of peripheral card  124  to the new peripheral card. 
     FIG. 2 provides additional detail relating to the construction of bank  116 . The Peripheral card  122  comprises a generally planar printed circuit board  200  having a forward end  202  and a rearward end  204 . An L-shaped bulkhead mounting bracket  206  has a first bracket segment  208  connected to the forward end  202  of the printed circuit board  200 , and a second bracket segment  210  extending forward of the first segment  208 . 
     The switch/latch mechanism  118  comprises the bulkhead  132 , which is adapted for mating engagement with the bulkhead mounting bracket  206  of the peripheral card  122  when the peripheral card  122  is installed in the switch/latch mechanism. The bulkhead  132  includes a first bulkhead wall  212  oriented in parallel to the first bracket segment  208  and a second bulkhead wall  214  oriented in parallel to the second bracket segment  210  when the peripheral card  122  is installed in the switch/latch mechanism  118 . The second bulkhead wall  214  includes an alignment pin  216  (see also pin  218  associated with neighboring paddle switch) for use in positioning the second bracket segment  210  on the second bulkhead wall  214 . 
     The switch housing  138  is deployed on a forward end  220  of the second bulkhead wall  214 . The switch housing includes a first switch wall  222  parallel to the first bulkhead wall  212  and a second switch wall  224  parallel to the second bulkhead wall  214 . 
     The switch/latch mechanism  118  includes a paddle switch  226  and a doorbell switch  228 . The paddle switch  226  is mounted on the switch housing  138  through use of a hinge axis  230  that permits the paddle switch  226  to travel in an arcuate path of motion over the second bulkhead wall  214 . The hinge axis  230  is oriented in parallel relationship to the first switch wall  222  and in perpendicular relationship to the second bulkhead wall  214 . The arcuate path of motion for paddle switch  226  extends between a locked position of normal operation above second bracket segment  210  and engaging the alignment pin  216 , as shown for paddle switch  226  in FIG. 2, and an interrupt position remote from the alignment pin  216 ; as shown by analogy to an identical paddle switch  232  that has been pivoted on hinge axis  234  to occupy an interrupt position in relationship to pin  218 . Peripheral card  126  may be removed without interference from paddle switch  226  when paddle switch  226  is rotated to the interrupt position. 
     The doorbell switch  228  is mounted in the second switch wall  224  and has a range of motion perpendicular to the second switch wall between the extended position of normal use, as shown in FIG. 2, and a compressed position where lip  236  abuts the second switch wall  224 . 
     The arrangement of identical teamed pairs of paddle switches and doorbell switches, in identical manner with respect to switch/latch mechanism  118 , provides an extremely compact structure that occupies a minimal footprint over dimensions of rise, width and depth. Accordingly, it is possible to enhance system cooling by the provision of a perforated wall  238  that rises above switch housing  138 . Alternatively, the perforated wall  238  may be eliminated to reduce the vertical profile of telecommunications server  100 . 
     An especially preferred but optional feature of the switch housing  138  is a modular construction comprising successive units  240  and  242  each capable of housing a portion of the plurality of paddle switch and doorbell switch pairs. The successive units  240  and  242  comprise clip-latch structure  244 ,  246  for engaging the second bulkhead wall  214  and the perforated wall  238  to retain the successive units  240  and  242  in fixed location with respect to one another. 
     FIG. 3 provides additional detail with respect to unit  240  of switch housing  138 . The first switch wall  222  defines a plurality of mushroom-shaped openings  300 ,  302 ,  304 , and  306 , that permit passage of components of the paddle switches, such as paddle switches  226  and  232  shown in FIG. 2. A series of downwardly extending male protrusions  308 ,  310 ,  312 ,  314 , and  316 , engage complimentary female structure on the second bulkhead wall  214 , as shown in FIG.  2 . Forwardly extending snap clips  318  and  320  engage the perforated wall  238 , as shown in FIG. 1, to retain the unit  240  in place. The second switch wall  224  defines square apertures  322 ,  324 ,  326  and  328  for receipt of doorbell buttons, such as doorbell button  330 . Ears  332 ,  334 ,  336 , and  338  each include a flexible snap slot, such as snap slot  340 , which is used to connect with a corresponding paddle switch, such as paddle switch  226  or  232 , as shown in FIG. 1. A forward facing channel slot recess  342  defined by the first switch wall  222 , the second switch wall  224 , and a third wall  344 . An elongated printed circuit board  346  snaps into the channel slot recess  342  and is there fixedly retained. 
     Beveled ends  348  and  350  are have complimentary structure such that a plurality of identical units may be placed end to end. Thus, a single unit  240  may be used in telecommunications servers having four, eight, twelve, sixteen or other multiples of four switch/latch mechanisms. Accordingly, in a large-scale production environment there is no need to manufacture and inventory different switch housings for the different servers because a single type of housing unit, such as unit  240 , provides a modular construction that meets the need of all of the servers. 
     FIG. 4 provides additional detail with respect to the printed circuit board  346 . While any type of switch, such as electrical contact switches may be used, a pair of identical optical switch components  400  and  402  are preferably used to enhance reliability of these switch components in operation. As shown in the case of switch component  402 , legs  404  and  406 , in combination with bight  408 , form a slot  410 . The optical switch component  402  contains an internal LED or laser diode  412  that emits light traveling from leg  402  to leg  404 . A complimentary photodetector (not shown) in leg  404  provides a continuous signal in response to emissions from diode  412  unless slot  410  is blocked by an obstruction. Slot  410  has a transverse orientation with respect to the axis of elongation in printed circuit board  346  and is used to accommodate a doorbell switch, such as doorbell switch  330  shown in FIG.  3 . Slot  414  has a parallel orientation with respect to the axis of elongation in printed circuit board  346  and is used to accommodate a paddle switch, such as paddle switch  226  shown in FIG.  2 . Metallized leads, such as lead  416 , operably interconnect the respective components of printed circuit board  346 . Slot  418  mates with a complimentary nib structure (not shown) on the third wall  344  of unit  240  for retention of the printed circuit board  346  in channel slot recess  342 , as depicted in FIG.  3 . Holes, such as hole  420  are used to engage the doorbell switches, as described in the context of FIG.  5 . 
     FIG. 5 provides additional detail showing the doorbell button  330  mounted in square aperture  326  from a forward perspective revealing channel slot recess  342 . Doorbell switch  330  comprises an uppermost table  500  having areal dimensions larger than those of square aperture  326 . A neck section  504  connects the table  500  with an integrally formed U-spring  506  having a distal end formed as a pivot rod member  508 . One end of the pivot rod member  508  fits into a hole, such as hole  510 , and another end  512  fits into a hole in printed circuit board  346 , such as hole  420  shown in FIG.  4 . Thus, U-spring  506  is able to exert upward bias on neck segment  504  and table  500  in compression against rod member  508  extending between first switch wall  222  and the printed circuit board  346 . An interrupt arm  514  is positioned for insertion into slot  410  (see FIG. 4) with disruption of the optical pathway between legs  404  and  406  by the downward motion of interrupt arm  514  in slot  410  against the bias of U-spring  506 . Snap retainers  516  and  518  extend downwardly from second switch wall  224  and deform to accept printed circuit board  346  into channel slot recess  342 . Printed circuit board  346  is positionally indexed to align slot  410  with interrupt arm  514  by a plurality of indexing studs, such as studs  520  and  522 , rising from third wall  344 . In preferred embodiments, all of the doorbell switches are identical to doorbell switch  330 . 
     FIG. 6 provides additional detail with respect to paddle switch  226 , which is also shown in FIG.  2 . In preferred embodiments, all of the paddle switches are identical to paddle switch  226 . A hinge pin  600  defines the hinge pivot axis  230 . The hinge pin  600  includes a lower male segment  602  extending beneath a panel body  602 . This lower male segment  602  is received into a complementary female opening in the second bulkhead wall  214 , as shown in FIG.  2 . The hinge pin  600  extends through panel body  602 , which forms a forward facing slot  604  that reveals a clipable segment  606  of the hinge pin  600 . This clipable segment  606  attaches to, for example, the snap slot  340  shown in FIG. 3. A panel surface  608 , as well as a corresponding panel surface remote from panel surface  608 , are textured with buttons  610  for ease of manual manipulation as panel body is pivoted about hinge pin  600 . The panel body  602  forms a snap slot  612  incorporating snap ears  614  and  616 . Snap ear  616  resides on a flexible sidewall  618  adjacent a recess  620 , which improves the flexibility of flexible sidewall  618 . The snap ears  614  and  616  resiliently deform to accommodate an alignment pin, such as pin  216  or  218  shown in FIG. 2, and retain the paddle switch  226  in locked position against vibrational forces during transit of the telecommunications server  100 . 
     A flag arm  622  protrudes forward of panel body  602  and is radially offset with respect to hinge pivot axis  230  and panel body  602 , such that rotation to a position of normal operation with alignment pin  216  (see also FIG. 2) received in slot  612  causes the flag arm  622  to move out of slot  414  (see also FIG. 4) with no optical interrupt in the slot  414 . Rotation of panel body  602  to disengage alignment pin  216  from slot  414  causes flag arm  622  to move into slot  414  where flag arm  622  causes an optical interrupt. 
     The foregoing discussion is intended to illustrate the concepts of the invention by way of example with emphasis upon the preferred embodiments and instrumentalities. Accordingly, the disclosed embodiments and instrumentalities are not exhaustive of all options or mannerisms for practicing the disclosed principles of the invention. The inventors hereby state their intention to rely upon the Doctrine of Equivalents in protecting the full scope and spirit of the invention.