Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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KEYING SYSTEM FOR CONNECTOR FAMILIES
This invention relates to keying systems for electrical connector
assemblies of the type comprising a receptacle having a plug receiving
opening therein and a plug which is received in the opening. The
5 embodiment of the invention described below shows the keying system as
provided on connector assemblies of the general types shown in U . S.
Patents 4,193,654, 4,210,376, and 4,331,458. The principles of the
invention can, however, be used to advantage with other types of
connectors.
lo US. Patents 4,193,654, 4,210,376, and 4,221,458 show a known type
of electrical connector assembly which is coming into widespread use in the
communications industry and on computer and computer related equipment.
The receptacles shown in the above-identified U . S . patents are
dimensioned to receive connector plugs of the general type shown in U . S.
Patent 3,860,316.
The receptacles and plugs referred to above usually have no more
than eight terminals therein and it is usually not considered necessary to
provide keying systems to key a particular plug to a particular receptacle.
However, there is a need for connector assemblies of the general type
20 described above having greatly increased numbers of contact terminals
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therein and there is a need for a family or series of connectors having
varying numbers of terminals therein. These requirements are particularly
felt by manufacturers of computers and computer-related equipment.
Where connector assemblies of the type under consideration are
5 manufactured in a range of sizes, as regards the number of terminals in
the assembly, it is possible to insert a plug part of the assembly having a
lesser number of contact terminals into a receptacle having a greater
number of contact terminals because of the fact that -the plug and
receptacle of two assemblies of different sizes differ only in the width of
10 the plug and the width of the plug-receiving opening in the receptacle. It
can readily be appreciate that as a number of connector assemblies of
different sizes are mounted adjacent to each other, a plug might be
mismated with a receptacle having a greater number of contact terminals
than the plug; in other words, the plug can be simply inserted into the
15 center portion of the plug-receiving opening of the receptacle. Obviously,
the connector system for the equipment must preclude this possibility to
avoid the potential for serious damage which might result from such
mismating. In accordance with one embodiment thereof, the invention is
directed to the achievement of a primary keying system for a series or
20 family of electrical connector assemblies, the primary keying system
functioning to prevent insertion of a relatively smaller plug into a larger
receptacle than the size of the receptacle for which the plug is intended.
I n addition to the need for a primary keying system, a conventional
keying system is also required for connector assemblies of the type under
25 consideration. If two connector assemblies of the same size (having the
same number of terminals therein are used in close proximity, it is
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possible to mismate the plugs and receptacles and the primary keying
system discussed above would not preclude such mismating. A secondary
keying system is thus needed specifically to keying a specific plug to a
specific receptacle. The invention in accordance with a further aspect is
5 directed to the achievement of an improved specific keying system and
particularly to a specific keying system in combination with a primary
keying system.
A preferred embodiment of the invention comprises a series of
electrical connector assemblies, each assembly comprising a plug and a
10 receptacle, each plug and each receptacle comprising a molded insulating
housing having a mating end and a rearward end and having oppositely
facing external housing sidewalls and oppositely facing external housing
endless extending from the mating end to the rearward end. Each of the
receptacles has a trough-like plug-receiving opening extending into its
15 mating end, the plug-receiving opening in each receptacle having opposed
plug opening sidewalls winch are proximate to the external housing
sidewalls and opposed plug opening endless which are proximate to the
external housing endless. The plug of each connector assembly has a
forward portion which extends from its mating end partially towards its
20 rearward end and which is dimensioned to be received in the
plug-receiving opening of the receptacle of the same assembly. A plurality
of plug contacts are provided in the plug of each assembly and a like
plurality of receptacle contacts in the receptacle of the same assembly.
The receptacle contacts are within the plug receiving opening and are
25 arranged in a row which extends between the plug opening endless. The
plug contacts of each plug are proximate to the mating end of the plug
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and are arranged in a row which extends between the plug housing
endless. The plug-receiving openings of the receptacles of the series are
of increasing width, as measured between the plug opening endless, with
increasing numbers of receptacle contacts in the receptacles, the plugs of
5 the series similarly being of increasing width, as measured between the
plug housing endless, with increasing numbers of plug contacts in the
plugs. The height of the plug openings, as measured between the plug
opening sidewalls, is uniform for all receptacles in the series. The series
of electrical connectors is characterized in that a primary keying system is
10 provided on the connector assemblies of the series, the primary keying
system comprising, on each assembly of the series, at least one primary
key on the receptacle of each assembly and at least one primary kiwi in
the plug of the same assembly, each primary key of the receptacle being
aligned with a corresponding primary kiwi of the plug of the same
1 5 assembly.
The primary keys and primary Casey of the connector assemblies of
the series having greater numbers of contacts are selectively located,
relative to the locations of the primary keys and primary Casey of
assemblies having lesser numbers of contacts, in a manner which prevents
20 insertion of a plug having a lesser number of contacts into a receptacle
having a greater number of contacts.
I n accordance with a further embodiment, a secondary keying system
is provided on the connector assemblies of the series for keying
specifically a specific plug of the series to a specific receptacle. In
25 accordance with a further embodiment, the secondary keys in the
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receptacles and secondary Casey in the plugs are dimensioned to
preclude entry of a primary key therein into a secondary kiwi.
A further embodiment comprises an electrical connector assembly of
the type comprising a molded plug and a molded receptacle, the plug and
receptacle being as described above. The assembly has a primary keying
system comprising at least one primary key on the receptacle and at least
one primary kiwi in the plug. Each primary key of the receptacle is
aligned with a corresponding primary kiwi of the plug of the assembly.
The primary keying system functions to permit insertion of the plug into
the plug-receiving opening of the receptacle and to preclude insertion of a
second plug, having a width as measured between its external housing
endless which is less than the corresponding dimension of the plug, into
the receptacle of the assembly.
In accordance with a further embodiment, a secondary keying system
is provided in addition to the primary keying system, the secondary
keying system functioning to prevent mismating of the plug and the
- receptacle with a substantially identical receptacle and a substantially
identical plug respectively, which have the same primary keying system as
the plug and receptacle.
I n accordance with a further embodiment, a plug shield and a
receptacle shield are provided on each plug and receptacle of the series.
The plug shield overlaps forward portions of the plug and extends to the
rearward end thereof. The forward portions of the plug have an
unshielded section which is adjacent to the mating end. The receptacle
shield is on the mating end of the receptacle and extends i no the
plug-receiving opening. The plug shield and the receptacle shield have
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shield contact portions which contact each other when the plug is inserted
into the receptacle. In one embodiment, the shield contact portions are
cantilever springs which are integral with the receptacle shield and which
extend into the plug-receiving opening.
FIGURE 1 is a perspective view showing an eight position connector
assembly in accordance with the invention with the plug exploded from the
receptacle.
FIGURE 2 is a cross-sectional view looking in the direction of the
arrows 2-2 of Figure 1 but with the plug in direct alignment with the receptacle.
FIGURE 3 is a semi-diagrammatic frontal view of the connector
receptacle showing the primary and secondary keys
FIGURES 4-15 are a series of diagral~natic views illustrating the
principles of the invention.
FIGURE 16, appearing on the same drawing sheet as Figure 3, is a view
similar to Figure 3 showing an alternative embodiment.
FIGURE 17, appearing on the same drawing sheet as Figure 3, is a
perspective view of a plug which is intended to be mated with the receptacle
of Figure 16.
FIGURE I is a perspective exploded view of a plug and a sheet metal
shield for the plug.
FIGURE 19 is a perspective exploded view of a receptacle and a sheet
metal shield for the receptacle.
FIGURE 20 is a cross-sectional view of a shielded plug inserted
into a shielded receptacle.
Figures 1-3 show an eight position connector assembly 2 comprising a
plug 4 and a receptacle 6. The assembly 2 incorporates a primary keying
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system and a secondary keying system in accordance with the invention.
The structure of the assembly will first be described in detail. The
relationship and significance of a keying system to a family or series of
connectors will then be descried with reference to Figures 4-15.
The plug 4 is generally in accordance with the teachings of U . S.
Patent 3,860,316 and comprises an insulating housing having mating end 8,
a rearward end 10, upper and lower housing sidewalls 12, 14 and
oppositely facing housing endless 16. Latch arms 18 extend from the
housing endless and have rearwardly facing shoulders 19 which engage
lo shoulders 61 in the receptacle when the plug is mated with the receptacle.A cable receiving opening 20 extends into the rearward end 10 and a
cable 22 is inserted into this opening. The individual conductors 24 of the
cable extend into a reduced cross section forward portion of the opening,
the cable being retained by an integral strain relief clamp 26 and the
conductors being retained by conductor strain relief means 28 as generally
described in US. Patent 3,860,3~6. The plug contact terminals 30
comprise flat stamped contact members and are received in recesses 32
which extend inwardly from the mating end 8 and inwardly from the lower
sidewall 14. The contact terminals have insulation piercing portions which
extend through openings and into the individual conductors 24. The plug
contacts are engaged with the spring contact portions 72 of the receptacle
contacts 62 when the plug is coupled to the receptacle.
The receptacle 6 is generally of the type shown in US. Patent
4,221,458 and comprises a one piece molded insulating housing having a
mating end 34, a rearward end 36, upper and lower external housing
sidewalls 38, 40, respectively, and oppositely facing external housing
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endless 42. A flange 44 is provided on the mating end 34 and overlaps
an opening in a panel 46. The receptacle is mounted on a circuit board 48
and may have integral interference-fit mounting projections 50 extending
from its lower sidewall 40.
A plug-receiving opening 52 extends inwardly from the mating end 34
and receives the forward portion 54 of the plug 4. The forward portion
extends from the mating end 3 of the plug for a substantial distance
towards the rearward end and portions of the latch arms 18 are received
in the opening 52 so that the shoulders 19 of the latches will engage the
shoulders 61.
Plug-receiving opening 52 has upper and lower plug opening sidewalls
56, 58 and opposed plug opening endless 60. The receptacle contacts 62
comprise flat stamped sheet metal members arranged in side-by-side
relationship in a row which extends between the plug opening endless 60.
Each contact 62 has a post portion 64 which extends beyond the housing
sidewall 40, through an opening in the circuit board, and is soldered to a
conductor on the underside of the circuit board. Each contact also has an
intermediate portion 66 which is received in a recess 68 extending inwardly
from the lower sidewall 40 and a contact spring portion 72 which extends
obliquely into the plug receiving opening. The contact is bent as shown
at 70 and is recessed from the mating end 34. The free end of the
contact portion 72 extends into a recess formed by spaced-apart barrier
walls 73 at the inner end of the opening 52. These barrier walls prevent
adjacent contacts from engaging each other. Barriers are also provided as
shown at 74 between the bent portions 70 of adjacent contacts.
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As shown in Figure 1, the central lower portion 76 of the receptacle
is open at the mating end to permit assembly of the contacts 62 to the
housing and bending of the contact portions 72 as explained in U . S.
Patent 4,221,458.
The primary keying system comprising primary keys 78 which are
molded integrally with the upper plug opening sidewall 56. Each key has
an inner end 80 which is adjacent to the rearward end 36 of the housing
and has a forward or outer end 82 which is located inwardly from the
mating end 34 of the receptacle housing. in the particular eight position
connector shown in Figures 1-3, two primary keys are provided in the
receptacle, these keys being on each side of the center line and closely
adjacent to the center line.
The corresponding primary Casey 84 in the plug 4 are dimensioned
to receive the primary keys and are located on each side of, and adjacent
to, the center line as required.
As shown in Figure 3, secondary keys 86 are provided on the upper
plug opening sidewall 56 and are coextensive with the primary keys 78.
The secondary keys 86 are of a generally square cross section and have a
width in the disclosed embodiment which is about one-half of that of the
primary keys. The secondary Casey 88 in the plug are coextensive with
the primary Casey 84 and are of reduced width as compared with the
primary Casey.
The functioning of the primary and secondary keying system will
now be explained with reference to Figures 4-15. These figures are
diagrammatic representations of the mating ends of a series of connector
parts having increasing numbers of contacts. The enclosed areas 93 thus
represent either the mating end 8 of the plug 4 or the mating end 34 of
the receptacle 6. Figures 4-15 are based on a series of connector
assemblies having four contacts in the smallest member of the series
(Figure 4) and having twenty-six contacts in the largest connector
5 assembly of the series figure 15). The intervening connector assemblies
of Figures 5-14 each has two more contacts than the previous connector
assembly. Thus Figure 5 represents a connector assembly having six
contacts, Figure 6 represents a connector assembly having eight contacts
and so on.
It The darkened rectangles 89 in Figures 4-15 represent the locations of
the primary keys 78 in the receptacles or the primary Casey 84 in the
plugs. The smaller undarkened squares 90 represent the possible sites for
secondary keys 86 or secondary Casey 88. It is possible to provide two
secondary key sites on the lower opening sidewall 58 of the receptacle and
15 corresponding Casey on the lower housing sidewall 14 of the plug as
shown at 92.
Careful study of Figures 4-15 will establish the fact that it would be
impossible to insert a plug 4 having a lesser number of contacts into a
receptacle 6 having a number of contacts therein which is greater than the
20 lesser number by virtue of the locations of the primary keys in the larger
receptacle and the absence of Casey in smaller plug. This fact can be
demonstrated by superimposing any one of Figures 4-14 on any other one
of the figures which has an identifying number greater than that of the
first figure. Figure 4 of the disclosed embodiment, the four position
25 connector assembly does not require a primary key and kiwi.
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In order specifically to key a plug and receptacle of the same size to
each other, a secondary key is provided in one of the secondary key and
kiwi sites 90, 92 in the receptacle and a corresponding kiwi is
provided in the plug. It will be noted that the secondary key and kiwi
5 sites 90, 92 have a width which is only about one-half that of the width of
the primary keys and Casey. It follows that there is no possibility that
a secondary kiwi will receive a primary key of a receptacle for which
the plug is not intended, in other words, a receptacle having a greater
number of contacts therein than the plug.
l Other relatively large number of potential sites for secondary keys and
Casey provides the capability of a large number of unique combinations
of secondary keys and Casey and therefore a correspondingly large
number of unique keying arrangements for connector assemblies within the
series or family. In the example for a connector family or series shown in
figures 4-15, the number of secondary key and Casey sites 90, 92 has
been limited to ten such sites . I n the larger size connector, additional
secondary key and kiwi sites could be provided as desired with a
resulting increase in the number of unique or specific keying combinations.
The primary and secondary keying systems of the invention can be
20 provided in a series of family of connector assemblies with relative ease in
the manufacturing process. The plug and receptacle shown in Figure 1
are such that they can be molded with a "straight action mold", that is, a
mold in which all of the core pins extend parallel to the direction of
movement of the mold halves towards and away from each other when the
25 mold is open and closed. A straight action mold is relatively simple as
compared with a "side draw" mold in which core pins extend normally of
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the direction of movement of the mold parts. The primary and secondary
Ices and Casey in the plug and receptacle are formed by core pins
which extend in the direction of movement of the mold parts. In the
embodiment shown, these core pins are of similar rectangular cross
section. It follows that core pins can be placed in the mold parts or
removed from the mold parts with relative ease to form the desired
secondary keys and Casey. The core pins which form the primary keys
and Casey would ordinarily remain permanently in the mold parts.
Figures 16 and 17 show an alternative embodiment in which a primary
l O key and one or two adjacent secondary keys are replaced by composite
keys as shown at 94 and 96 in Figure 16. This expedient might be
employed if the secondary keys require strengthening and if it is found to
be impractical to form the very thin webs or barrier walls in the plug
between the primary kiwi and the secondary kiwi. The composite
key 94 thus comprises a primary key, a secondary key, and molded
material which fills the gap between the two keys. The composite key 96
comprises a primary key and two secondary keys in addition to the
material between the primary key and the secondary keys. The composite
Casey 99, 101 for the composite keys 94, 96 are sufficiently wide to
accept the composite keys as shown in Figure 17. The connector 4 also
has modified latch arms 103 and is provided with a shield 98 as described
below .
Figures 18, 19, and 20 show features of a shielded connector
assembly in accordance with the invention. The cable 22' has metallic
shielding 102 in surrounding relationship to the conductors 24 and an
insulating sheath 104 surrounds the shielding material 102.
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The plug 4 and receptacle 6 of Figures 18 and 19 are substantially
similar to the previously described plug and receptacle and are identified
with the same reference numerals.
The plug shield 98 is of sheet metal and has an upper sidewall 106, a
lower sidewall 108, and oppositely facing endless 110 which are against
the corresponding sidewalls and endless of the plug housing. The
forward end 112 of the shield 98 is recessed from the mating end 8 of the
housing so that a forward portion 54 of the housing is not covered by the
shield. The rearward end 114 of the shield has an inwardly turned flange
l O 116 which is maintained in contact with the shielding material 102 by the
locking member 26. l tongues 118 are provided on the lower sidewall 108
and can be bent into recesses in the plug housing to retain the shield on
the housing . The shield is also retained by a boss 120 on the upper
sidewall 12 of the plug housing which is received in an opening 121 of the
l 5 shield.
The receptacle shield 100 has a face portion 122 which is disposed
against the mating end of the receptacle housing and has a flange 124
which extends over the flange 44 of the receptacle housing. Clinching
ears 126 extend from this flange as shown in Figure 20 to retain the
receptacle shield 100 on the receptacle housing .
A tongue 128 extends from the flange 124 partially across the lower
housing sidewall and may be electrically connected to a ground conductor
on the circuit board if desired . Contact arms 130 extend from the
plug-receiving opening of the shield 100 and are engaged by the receptacle
shield when the parts are mated with each other as shown in Figure 20.
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As is apparent from Figure 20, the shielding material 102 is in
electrical contact with the plug shield 98 and the forward portion of the
plug shield is received in the plug-receiving opening of the receptacle so
that the plug shield overlaps the receptacle shield. There is thus no
5 possibility of radiation from the conductors and contacts.
The shielding members 98, 100 of Figures 18-20 are entirely
compatible with the primary and secondary keying systems previously
described. The primary and secondary keys in the receptacle are
recessed inwardly from the mating end of the receptacle so that these keys
l o do not interfere with the shielding of the receptacle. Also, the plug
shield does not cover the forward portion of the plug housing and the
Casey 84, 88 will cooperate with the keys to achieve the keying effects
described above.
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