Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-10-08
2001-07-31
Gandhi, Jayprakash N. (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S754000, C361S798000, C361S801000, C361S726000, C439S157000, C211S041170
Reexamination Certificate
active
06269007
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for securing a rigid plate and, in particular, to a multiple actuator latch used to secure a circuit board.
2. Description of the Related Art
System flexibility is a highly desirable trait which allows a system to respond to the changing needs and/or requirements of a user or group of users. One solution to the need for flexibility is the incorporation of interchangeable parts within such systems. This is especially true in electronics applications, where interchangability of parts increases the lifespan and functionality of a system. Interchangeable parts may be switched, upgraded, or removed without having to replace the entire system. One such interchangeable part often used in computer-based applications is the printed circuit board (PCB). Computer systems may be fabricated to use a plurality of PCBs, each containing a portion of the electronics required to allow the computer system to operate.
To address the need for interchangeability in complex electronics applications, e.g. computer systems, “card racks” (or “card cages”) have been developed. A card rack is a relatively large enclosure containing racks or shelves capable of holding a number of PCBs in a parallel configuration. A typical card rack
500
holding a number of PCBs
501
is shown in FIG.
8
. Card rack
500
consists of side plates
502
and
503
connected by supports
504
. A backplane
505
is connected to side plates
502
and
503
and includes electrical connectors
506
, at least one connector
506
being provided for each of the PCBs
501
. Connectors
506
releasably engage connectors
507
on the PCBs
501
to allow communication between the PCB
501
and the system of which card rack
500
is a portion. Plug
508
is inserted through aperture
509
into engagement with pin connectors to complete the physical installation of the PCBs
501
.
Card racks and PCB's are found in numerous telecommunications applications, e.g. line units and trunk units. PCBs
501
for telecommunications applications may be in the form of circuit packs
516
, as shown in FIG.
9
. Each circuit pack
516
includes a plurality of signal processing components
518
mounted on a planar surface
520
of a rigid plate
522
. The rigid plate
522
includes conductive paths
524
for interconnecting the components
518
to one another and to connector
507
. Connector
507
is mounted on the rigid plate
522
, generally on an end face of the rigid plate
522
. The connector
507
contains pins and/or sockets for mating with matching connectors fixedly mounted on a rear wall of a card rack. Circuit pack
516
, a specific type of PCB
501
, may be removably mounted in a side-by-side, parallel relationship within a card rack
500
relative to other PCBs
501
and side plates
502
,
503
, as shown in FIG.
8
.
The circuit pack
516
has a front face plate
528
which is mounted to the rigid plate
522
. Mounting and dismounting of the circuit pack
516
occurs by sliding the edges of the rigid plate
522
along grooves within support walls of the card rack
500
. Latches
530
are provided on the face plate
528
or rigid plate
522
to allow the circuit pack
516
to be secured to the card rack
500
.
A known latch
530
is shown in FIG.
10
. The latch
530
consists of a body portion
532
; a handle portion
534
comprising both an actuating member
536
and a stop portion
538
; a locking portion
540
; a hooked portion
542
; and a pivot point
544
which is used to pivotally mount latch
530
to rigid plate
522
. The portion
545
of latch
530
nearest the rigid plate
522
is split into two sections to a depth defined by dotted line
547
which allows latch
530
to straddle the edge
549
of rigid plate
522
. In operation, the latch
530
is pivoted about a pin
546
and pivot point
544
until locking portion
540
contacts an inside surface of card rack
500
. The latch
530
is secured by applying downward pressure, e.g. through an operator's finger, in direction
550
to actuator
536
which allows hooked portion
542
to be raised above pin
548
. While retaining downward pressure in direction
550
, additional pressure is placed on the actuator
536
in direction
552
until hooked portion
542
passes over pin
548
. The pressure on actuator
536
is then released, e.g. by the operator removing the finger, allowing hooked portion
542
to be lowered and engage pin
548
. To release the latch
530
, downward pressure is again applied to actuator
536
which raises hooked portion
542
and allows the latch
530
to become disengaged from pin
548
and rotate freely in the reverse of direction
552
.
Latches
530
of the type shown in
FIG. 10
are susceptible to inadvertent or accidental removal of the rigid plate
522
. A single motion on the actuator
536
may cause the latch
530
to become disengaged and allow the circuit pack
516
to be removed. In addition, if an actuator
530
becomes weakened or loose (e.g. from use, environmental conditions, etc.) the latch
530
may become disengaged. Such a result is not only undesirable, but may result in large-scale system failure if an essential circuit pack
516
is inadvertently removed.
Thus, there exists a need for a securing mechanism for a circuit board which prevents accidental or inadvertent removal of the board once it is inserted and connected into a card rack.
SUMMARY OF THE INVENTION
The present invention provides a latch that is able to secure a printed circuit board or circuit pack to a card rack while preventing its accidental or undesired removal. In a preferred embodiment, the latch includes at least two actuators flexibly mounted to a body. Each actuator has a hooked portion for securing the actuator from movement and a lever portion to release the hooked portion. The body is pivotably mounted to a circuit board or circuit pack. When fully latched, the object is secured to a card rack by the hooked portion. The hooked portion is capable of being moved when the body is rotated about the pivot point. Rotation occurs when the actuators are released through use of the lever portions. To prevent unintended removal of a circuit board or circuit pack secured by the latch, the second actuator may not be released until the first actuator has been released. The latch thus requires at least two actions, pressing the lever portions in succession, to release the circuit board or circuit pack from a card rack.
REFERENCES:
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patent: 4313150 (1982-01-01), Chu
patent: 4632588 (1986-12-01), Fitzpatrick
patent: 4648009 (1987-03-01), Beun et al.
patent: 4780792 (1988-10-01), Harris et al.
patent: 4947289 (1990-08-01), Dynie
patent: 4996631 (1991-02-01), Freehauf
patent: 5316488 (1994-05-01), Gardner et al.
patent: 5398164 (1995-03-01), Goodman et al.
patent: 5502622 (1996-03-01), Cromwell
patent: 5504656 (1996-04-01), Joist
patent: 5632641 (1997-05-01), Sobel
patent: 5889850 (1999-03-01), Sochacki
patent: 5892662 (1999-04-01), Verma
Pongracz David John
Smith Steven J.
Dickstein , Shapiro, Morin & Oshinsky, LLP
Gandhi Jayprakash N.
Lucent Technologies - Inc.
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