Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-07-27
2001-01-16
Gandhi, Jayprakash N. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S752000, C361S803000, C439S928100
Reexamination Certificate
active
06175508
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to hardware configurations for electronic circuits, such as those used in telecommunication equipment, and is particularly directed to a new and improved circuit card architecture, that is installable in a respective card slot of a cabinet or rack for electrical and physical engagement with a backplane connector, and which includes a face plate that forms part of the front panel of the cabinet in which the card is installed.
BACKGROUND OF THE INVENTION
For space efficiency and ease of access to circuit components, housing configurations for electronic circuits, such as those employed in channel banks of telecommunication equipment, such as a D4 channel bank customarily contain a plurality of parallel circuit card slots having parallel card guide and support tracks, that are sized to receive respective electronic circuit cards which plug into electrical backplane connectors at a rear portion of a cabinet or rack.
FIGS.
1
-
3
diagrammatically illustrate a typical example of standard printed wiring board or card
10
that is configured to engage a backplane connector. For purposes of providing a non-limiting example, FIGS.
1
-
3
show the backplane connector configured as a card edge connector which receives and engages a plurality of lead conductor traces
12
that extend to a first or rear end of the card
10
. The card
10
itself has a prescribed industry standard size and shape (‘form factor’), and is typically made of a generally longitudinal rectangularly shaped sheet of fiberglass.
The lead connector traces
12
are connected to circuit components
13
mounted on the board proper by way of patterned conductive material
14
that has been selectively etched onto the fiberglass sheet of which the printed wiring board
10
is made. The lead connector traces
12
are sized and arranged to engage associated conductors along the interior sides of a backplane connector
15
, when the rear end of the card
10
is physically inserted into and is captured by the connector, thereby providing backplane connections to the circuit components of the card. The backplane connector further serves to physically capture and thereby stabilize the card in its card slot.
A second (front) end
16
of the card
10
is affixed to a (metallic) face plate or front panel
17
, that is sized to fit within and thereby close a portion of a card slot opening
18
at the front of the equipment rack. Upper and lower card slot guide tracks
19
and
20
are sized to receive upper and lower edges
21
and
22
, respectively, of the card
10
, so that, as the printed circuit card
10
is inserted into the cabinet through the card slot opening
18
, it slides within the guide tracks
19
and
20
until the rear end
11
of the card containing the conductive traces
12
is physically plugged into and captured by the backplane connector
15
. Once installed in its card slot, the card's form factor will place the face plate coincident with the front panel of the rack, thereby closing the card insertion opening.
Now although continuing improvements in the semiconductor industry have enhanced the microminiaturization of electronic circuit components, and thereby reduced the size of the components themselves and the printed circuit board real estate required to implement such circuits, such as the telecommunication circuits of channel bank installations, telecommunication service providers are not readily desirous of replacing an existing piece of equipment simply because it can be made somewhat smaller or housed in a more compact configuration. Indeed, the axiom “if it ain't broke, don't fix it,” can be considered to apply to telecommunication equipment configurations that have been and can be expected to continue to provide satisfactory service to telco customers.
This is especially true in the case of relatively low end, standardized circuit cards, whose principal driving force is cost, where the cheaper the card can be produced, the better. Since such cards have a relatively fixed, universal form factor, and employ circuit components whose integration densities have essentially stabilized, namely, reached a point that no longer provides a substantial reduction in the cost of the circuit, per se, the circuits themselves are now essentially fixed cost items to the circuit card supplier.
SUMMARY OF THE INVENTION
In accordance with the present invention, the desire to further reduce the cost of printed wiring board-implemented circuits, such as, but not limited to, those employed in telecommunication channel bank equipment, (such as a D4 channel bank) referenced above, where the circuits per se are essentially standardized, fixed cost items, is readily accomplished by a new and improved ‘composite’ circuit card architecture, which configures only a necessary portion of the composite circuit card of printed wiring board material, rather than the entire card, as in conventional configurations. As pointed out above, the ability to employ a reduced size printed wiring board results from the improvements in integration density to circuit sizes that are now considerably smaller than or only a fraction of the available mounting area of the standard card form factor. The remainder of the card architecture, including the front panel, where no printed circuit components are installed, is formed of a material, such as molded plastic, which is less costly than that of the printed wiring board, thereby significantly reducing the cost associated with the conventional approach of making the entire card from printed circuit board material.
Namely, the ‘composite’ circuit card architecture of the present invention is essentially comprised of two principal components—a form factor conformal or compatible ‘pseudo’ circuit card, which is preferably made of an injection molded plastic material, that is considerably less expensive than standard printed circuit card material (a printed circuit-patterned fiberglass sheet), and—a reduced size or non form factor-conformal printed circuit board. The pseudo circuit card includes a generally rectangular card-shaped support substrate as a supporting motherboard and a front panel integrally molded therewith. By form factor conformal or compatible is meant that the support substrate is dimensioned to generally correspond to the size and shape of an industry standard printed circuit card, described above.
As will be more fully appreciated from the detailed description to follow, by making as much of the inventive circuit card as possible out of a relatively inexpensive material (here, the entire pseudo card, including all of the support substrate and the front panel, as well), for example, using an injected molded plastic process through which plastic multiple cards (which may contain varying irregularities) are easily reproduced, not only is the cost of the actual materials within the finished card substantially reduced, but the cost of material that would otherwise be wasted, but still used in the manufacturing process, is minimized.
As a simple comparison, in a conventional form factor compatible card, the front panel is made of formed metal (such as, but not limited to brushed, extruded or cast aluminum), while the entirety of the card material, to which the metallic front panel is attached, and which fits into the card slot and engages the backplane connector, is cut out from a sheet of standard fiberglass printed wiring board. Any trimming of such wiring board material into the final shape of the card will necessarily leave scrap printed circuit fiberglass as unusable and costly waste. In contrast, the circuit card architecture of the present invention uses only that amount of printed fiberglass wiring board that is necessary to implement the functionality of the signal processing circuit of interest. Any remaining material required for physical support and for realizing an overall form factor-compatible card configuration is made of a less costly, but mechanically equivalent, material, such as injection molded
McMillian Lonnie S.
Schofield Wade S.
Smith Barry S.
Adtran Corporation
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Gandhi Jayprakash N.
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