Electrical transmission or interconnection systems – Conductor arrangements or structure
Reexamination Certificate
1999-04-02
2001-10-30
Cuneo, Kamand (Department: 2841)
Electrical transmission or interconnection systems
Conductor arrangements or structure
C174S261000
Reexamination Certificate
active
06310412
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention is directed generally to printed circuit boards and related connectors, and more particularly, to a system and method for providing distribution of three-phase alternating current (“AC”) on a printed circuit board.
2. Description of the Prior Art
Companies that develop electronic equipment for three-phase AC operation face the challenge of designing a power distribution system that meets the requirements of organizations, such as Underwriters Laboratories Inc. (“UL”) and the Canadian Standards Association (“CSA”). Also, in a global economy, equipment often needs to be compatible with both the 120V three-phase AC environment found in the United States and Japan and the 220V three-phase AC environment found in other countries, particularly in Europe. The design task is even more complicated when three-phase alternating current must be distributed on a printed circuit board where space on the board is often limited.
FIG. 1
shows a prior art system
10
for distributing three-phase alternating current on a printed circuit board
12
. The system
10
comprises a connector
14
having a plurality of pins (e.g., pin
16
) and a corresponding plurality of traces
20
-
28
, each of which is electrically connected to one or more of the respective pins via a solder pad (e.g., solder pad
18
). As is common in the prior art, each of the pins connected to traces
22
,
24
, and
26
are defined to carry one of the three phases of the alternating current. Three of the other pins are collectively connected to a single trace
20
defined as a neutral. Trace
28
and its corresponding pin are undefined in this example. As is common with this type of system, the pins of the connector
14
are arranged substantially in a line and are spaced equidistantly from each other, i.e., the spacing, S, between the different solder pads (and associated traces) on the printed circuit board
12
is uniform.
With respect to the three-phase AC distribution system illustrated in
FIG. 1
, regulatory agencies and other organizations have set certain minimum safety requirements for the spacing, S, between adjacent traces that carry the different phases for a three-phase AC distribution. Unfortunately, the minimum spacing requirements are different in the United States and Japan than the requirements in Europe, mainly as a result of the different operating voltages in those regions—120 V in the United States and Japan, 220V in Europe. Specifically, for 120V three-phase AC distribution, two traces that carry respective phases of the AC must be spaced apart at least 2.5 millimeters. For 220V three-phase AC distribution, the spacing must be a minimum of 3.2-4.0 millimeters. A problem that arises as a result of these differences is how to design a three-phase AC distribution system for a printed circuit board that can operate in both 120V and 220V environments.
One solution to the minimum spacing problem is simply to use a larger connector designed with larger clearances for boards that will be operated in the larger voltage environment. Another solution for larger voltages is to use a separate connector for each of the different phases. Unfortunately, these solutions are disadvantageous because they require more room on the printed circuit board and a more expensive connector solution. A more preferable solution would allow a single three-phase AC distribution system to be used in both environments while optimizing distribution density and reducing cost. The present invention satisfies this need.
SUMMARY OF THE INVENTION
The present invention is directed to a system and method for distributing three-phase alternating current (AC) on a printed circuit board. The system comprises a connector having a plurality of pins and a corresponding trace on the printed circuit board for each of the pins. The spacing between adjacent traces satisfies a first minimum spacing requirement, and the spacing between alternating traces (i.e., “every other” trace) satisfies a second minimum spacing requirement larger than the first minimum spacing requirement. When the three-phase AC distribution system of the present invention is employed in an environment that imposes the second, larger minimum spacing requirement, the traces are defined such that the different phases of the alternating current are carried on alternating traces (i.e., “every other” trace), with the traces in between defined as neutrals. When the three-phase AC distribution system is employed in an environment that imposes the first, lesser minimum spacing requirement, the traces can be defined such that the different phases of the alternating current arc carried on adjacent traces. This optimizes distribution density while enabling the same system to be used in environments that impose either of two different minimum spacing requirements between phase carrying traces. Preferably, at least one of the spacings is equal to the respective minimum spacing requirement that it satisfies, thus obtaining the most optimum allowable distribution density.
A method for distributing three-phase alternating current on a printed circuit board in accordance with the present invention comprises:
providing a connector having a plurality of pins;
providing a corresponding trace on the printed circuit board for each of the pins, the spacing between adjacent traces satisfying a first minimum spacing requirement and the spacing between alternating traces satisfying a second minimum spacing requirement larger than the first minimum spacing requirement;
defining the traces such that the different phases of the alternating current are carried on alternating traces with the traces in between defined as neutrals, when the system is employed in an environment that imposes the second minimum spacing requirement; and
defining the traces such that the different phases of the alternating current are carried on adjacent traces, when the system is employed in an environment that imposes the first minimum spacing requirement.
Additional features and advantages of the present invention will become evident hereinafter.
REFERENCES:
patent: 3543198 (1970-11-01), Stopper
patent: 4045750 (1977-08-01), Marshall
patent: 4130723 (1978-12-01), Wakeling
patent: 4707671 (1987-11-01), Suzuki et al.
patent: 4798918 (1989-01-01), Kabadi et al.
patent: 5497037 (1996-03-01), Lee et al.
patent: 5844783 (1998-12-01), Kojima
Cuneo Kamand
Rode Lise A.
Starr Mark T.
Unisys Corporation
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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