Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to backpanel assemblies, and to
electronic apparatus including such assemblies.
It is well known to provide electronic apparatus, such as
telecommunications equipment, with a backpanel having a plurality of
elongate printed circuit board (PCB) connectors aligned in parallel
thereon, into which PCBs are inserted to carry out desired functions.
This backpanel, which for example is itself a multi-layer PCB, provides
desired interconnections between the PCBs, and enables the supply of
siynals and power thereto, via the PCB connectors.
The PCB connectors of a backpanel assembly are generally
formed by pins extending from the backpanel and surrounded by a shroud
which serves to protect the pins and to guide a mating connector on a PCB
into engagement and electrical contact with the pins. Commonly each
connector comprises two rows of pins. It is also known to provide pins
which extend completely through the backpanel and project from each face
thereof, the pins extending from each face of the backpanel being
surrounded by a respective shroud to form a respective PCB connector,
whereby the number of PCB connectors provided in the backpanel assembly is
doubled. In this case the PCBs inserted into the connectors extend on
both faces of the backpanel so that the backpanel is situated
therebetween; however, the term "backpanel" is still used in this case.
In such apparatus it is desirable to facilitate expansion by
arranging the backpanel so that the apparatus can initially operate with
relatively few PCBs inserted, and can continue operation with greater
capacity by inserting more PCBs into the backpanel connectors. Generally
this means providing a bus system of interconnecting the PCB connectors on
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the backpanel, with correspondingly-positioned pins in many PCB
connectors being connected together.
A problem arises, however, if different numbers and
arrangements of PCBs of one type, for example processor boards, are
required to be interconnected to varying numbers and arrangements of
boards of other types, for example peripheral or interface boards, via
respective busses which are different for the different processors.
For example, in an initial implementation of electronic
apparatus it may be desired to have a single processor board and a few
peripheral boards interconnected thereto via the backpanel. For greater
capacity it may then be desired to add further peripheral boards, again
interconnected to the single processor board via the backpanel. With
greater numbers of peripheral boards, it may be desirable subsequently to
provide one or more additional processor boards, each to operate
independently of the other processor boards in association with a
respective one or more peripheral boards via a respective set of
interconnections. However, known backpanel assemblies do not conveniently
allow for this.
Accordingly, an object of this invention is to provide an
improved backpanel assembly, and electronic apparatus including such an
assembly.
According to this invention there is provided a backpanel
assembly comprising a backpanel having a plurality of elongate printed
circuit board (PCB) connectors aligned in parallel on a first face
thereof, each PCB connector including first and second groups of pins
which extend from the PCB connector through the backpanel to form at least
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part of a PCB connector on a second face of the backpanel, the first and
second groups of pins having equal numbers of pins, the individual pins of
the first and second groups of pins in adjacent PCB connectors on the
first face of the backpanel being respectively interconnected via the
backpanel; a plurality of PCBs each inserted into a respective PCB
connector on one of the faces of the backpanel and having electrical
connections to pins of the first group but not to pins of the second group
of the respective PCB connector; at least one PCB inserted into a PCB
connector on the other face of the backpanel opposite a respective one of
said plurality of PCBs, said at least one PCB having electrical
connections to pins of the first group but not to pins of the second group
of the respective PCB connector; and at least one connecting means
inserted into a PCB connector on said other face of the backpanel opposite
a respective one of said plurality of PCBs, said connecting means
electrically interconnecting individual pins of the first and second
groups of pins of the respective connector.
Conveniently each PCB connector comprises two rows of pins
extending along its length, the first and second groups of pins comprise
pins which are positioned adjacent one another in the respective rows, and
the pins in the adjacent PCe connectors which are interconnected via the
backpanel are interconnected via printed circuit backpanel wiring
extending perpendicularly to the PCB connectors.
The invention will be further understood from the following
description with reference to the accompanying drawings, in which:
Fig. 1 schematically illustrates part of a backpanel
assembly;
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Fig. 2 schematically illustrates the manner in which
printed circuit boards (PCBs) are inserted into connectors on the
backpanel assembly;
Fig. 3 schematically illustrates in a diagrammatic
cross-sectional view electrical interconnections achieved between PCBs via
the backpanel assembly.
Referring to the drawings, a backpanel assembly 10 is shown
in part in Fig. 1 and in part in a cross-sectional view in Fig. 2. The
backpanel assembly 10 comprises a backpanel 12, which is in the form of a
multi-layer PCB, and a plurality of elongate PCB connectors 14 aligned in
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parallel thereon. Although the connectors 14 can be of other known forms,
conveniently and as illustrated in Figs. 1 and 2 each connector 14
consists of two rows of pins 16 surrounded by a shroud 18 (shown in broken
lines in Fig. 1 for clarity) which serves to protect the pins 16 and to
guide a connector 20 (Fig. 2) on each PCB 22 into engagement and
electrical contact with the pins when the PCB 22 is inserted into the
connector 14.
As illustrated in Fig. 2, the pins 16 extend completely
through the backpanel 12 so as to project from each face thereof, and are
surrounded by respective shrouds 18 to form respective PCB connectors 14
directly opposite one another on respective faces of the backpanel
assembly 10. Accordingly, PCBs 22 can be inserted into connectors 14 on
both sides of the backpanel assembly 10, as illustrated in Fig. 2 by
arrows 24, the PCBs being guided into proper position for inter-engagement
of the connectors 20 and 14 by means of guide rails (not shown) at edges
of the PCBs, as is well known.
The backpanel assembly 10 is intended to accommodate at
least two types of PCBs 22, which are referred to here as processor (PR)
boards and peripheral or interface (PI) boards, in various numbers and
arrangements. Interconnections between these boards are achieved in a
manner which is described below with reference to Figs. 1 and 3. In
addition to the interconnections discussed specifically below, the boards
may be interconnected among themselves, and may be connected to other
apparatus, via the PCB connectors 14 and the backpanel 12 in any known
manner, for example for the supply of power and signals commonly to the
boards. As the known arrangements of such conventional connections form
no part of this invention, they are not further described here. However,
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the presence of such other connections is indicated in Fig. 1 by the
presence of four pins 16, at the top of each connector 14 as shown in Fig.
1, which together with other pins (not shown) may serve for such
connections.
Referring to Fig. 1, the two rows of pins 16 of each
connector 14, for specific interconnections between the PCBs 22, are
divided into two equal groups. For convenience the left-hand row, as
shown in the drawings, of pins 16 in each connector 14 forms one of these
groups, and the right-hand row, as shown in the drawings, of pins 16 in
each connector 14 forms the other group. However, any other division of
the pins 16, with interconnections corresponding to those described below,
may be provided.
As illustrated, each pin 16 of the right-hand row of pins of
each connector 14 is connected to a correspondingly-positioned pin 16 of
the left-hand row of pins of the connector 14 immediately to the right, by
a respective printed circuit track 26 of the backpanel 12. The tracks 26
thus form segmented busses across the backpanel 12, each segment extending
between corresponding pins 16 on opposite sides of adjacent connectors 14.
One such segmented bus 28 is diagramatically illustrated in Fig. 3, in
which the backpanel 12 is indicated by broken lines for clarity, and one
set of correspondingly-positioned pins 16 on the left-hand and right-hand
sides of the connectors 14 is represented by electrical connecting lines
also referenced 16.
All of the PR boards and all of the PI boards are arranged
to be electrically connected via their connectors 20 with only one of the
two equal groups of pins. In Fig. 3 it is assumed that this is the
left-hand (as illustrated) row of pins. This selection is relatively
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arbitrary, but is consistent for all of the PR and PI boards. For
convenience, as illustrated in Fig. 3 all of the PI boards are inserted
into connectors on one face of the backpanel 12, and all of the PR boards
are inserted into connectors on the opposite face of the backpanel. Fig.
3 illustrates six PI boards 31 to 36 and three PR boards 41, 45 and 46,
and in addition illustrates three bus extender (BE) boards 52 to 54 which
are described below. Fig. 3 illustrates clearly by connections
represented by arrowed lines 30 that each PR and PI board is electrically
connected to the left-hand pin, and not to the right-hand pin, of the
respective connector.
Each of the BE boards comprises a PCB which is inserted into
a connector 14 in place of a PR board and which contains electrical
connections between the left-hand and right-hand groups of pins. Each such
electrical connection serves to join together two adjacent segments or
tracks 26 of the respective segmented bus, whereby the bus is extended
between the segments aross the respective connector 14. Fig. 3
illustrates this for the one segmented bus 28 shown, electrical
connections 60 on the BE cards 52 to 54 forming a continuous bus from the
left-hand pins of the connectors for the boards 35 and 45 to the
right-hand pins of the connectors for the boards 31 to 41, The other
segmented busses are extended in the same manner,
From the above description and the drawings, it should be
appreciated that the PR board 46 and the PI board 36 are interconnected
via the left-hand pins of their respective connectors 14, but are not
connected to other boards. The PR board 45 is connected in a similar
manner to the PI board 35, and also the PI boards 34, 33, and 32 by virtue
of the presence of the BE boards 54, 53, and 52 respectively. The PR
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board 41 and the PI board 31 are interconnected via the left-hand group of
pins of their connectors 14, but are not connected to any of the boards to
their right (as illustrated) because they do not connect to the right-hand
group of pins of their connectors, and may or may not be connected to
other boards to their left depending on the presence or absence of other
BE boards (not shown).
Although in Fig. 3 boards are shown in all possible
positions, this need not be the case. For example, the PI board 32 need
not be present, and the corresponding BE board 52 may be consequently
omitted or not as desired. Furthermore, any of the PI boards 32 to 35 may
be removed without affecting the interconnections between the PR board 45
and the remaining ones of these PI boards.
Furthermore, it should now be appreciated that the
arrangement described is particularly amenable to modification and
expansion. For example, if it is determined that the functions of the PR
board 41 can be handled by the PR board 45, then this can readily be
achieved simply by replacing the PR board 41 with a BE board. Conversely,
if it is determined that an additional PR board should be provided to
share with the PR board 45 the handling of functions for the PI boards 32
to 35, such an additional PR board can be provided in place of one of the
BE boards 52 to 54, depending on the sharing of functions which is
desired, to achieve this.
Although a particular embodiment of the invention has been
described, it should be appreciated that numerous modifications,
variations, and adaptations may be made thereto without departing from the
scope of the invention as defined in the claims. For example, as already
observed the two groups of pins which are linked by the BE boards can be
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selected in any desired manner, and need not be in separate rows as in the
embodiment described. In addition, the BE boards may be provided with
logic or other circuitry (e.g. bus drivers) for effecting interconnections
between the two groups of pins, and may optionally interconnect only some
of the pins of the two groups, to suit particular requirements.
In addition, it is observed that the invention is applicable
to equipment using other than the processor and peripheral or interface
boards described above, and that other physical arrangements of the boards
may be provided. For example, instead of having the PR and PI boards on
opposite sides of the backpanel as described above, they could all be
provided on the same side of the backpanel with BE boards on the opposite
side as desired to extend the segmented busses between those adjacent PR
and PI boards requiring interconnections. In this case it is observed
that the BE boards could be reduced in size to the extent that they
consist of mere plug-in jumpers between the pins requiring
interconnection.
