[0001] 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
embodiment of the invention described below shows the keying system as provided on
connector assemblies of the general types shown in US 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.
[0002] 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
US patents are dimensioned to receive connector plugs of the general type shown in
US patent 3 860 316.
[0003] 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 described above having greatly increased numbers of
contact terminals 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.
[0004] Where connector assemblies of the type under consideration are 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 the plug and the width of the plug-receiving opening in the receptacle. It
can readily be appreciated 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 centre portion of the plug-receiving opening of the receptacle.
Obviously, the connector system for
1_he 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 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.
[0005] In addition to the need for a primary keying system, a conventional keying system
is also required for connector assemblies of the type under consideration. If two
connector assemblies of the same size (having the same number of terminals therein)
are used in close proximity, it is 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 directed to the achievement
of an improved specific keying system and particularly to a specific keying system
in combination with a primary keying system.
[0006] In our application EP-A-0 108 477 from which the present application is divided we
have disclosed and claimed a series of electrical connector assemblies, each assembly
comprising a plug and a 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 endwalls extending
from the mating end to the rearward end, each of the receptacles having a trough-like
plug-receiving opening extending into its mating end, the plug-receiving opening in
each receptacle having opposed sidewalls which are proximate to the external housing
sidewalls and opposed endwalls which are proximate to the external housing endwalls,
the plug of each connector assembly having a forward portion which extends from its
mating end partially towards its 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 in the plug of each assembly and a like plurality of receptacle contacts
in the receptacle of the same assembly, the receptacle contacts being within the plug-receiving
opening and being arranged in a row which extends between the endwalls thereof, the
plug contacts of each plug being proximate to the mating end of the plug and being
arranged in a row which extends between the plug-housing endwalls, the plug-receiving
openings of the receptacles of the series being of increasing width, as measured between
the endwalls thereof, with increasing numbers of receptacle contacts in the receptacles,
the plugs of the series similarly being of increasing width, as measured between the
plug-housing endwalls, with increasing numbers of plug contacts in the plugs the height
of the plug openings, as measured between the sidewalls thereof, being uniform for
all receptacles in the series, the series of electrical connectors . is characterised
in that a primary keying system is provided on the connector assemblies of the series,
the primary keying
pystem comprising, on each assembly of the series, at least one primary key on the
sidewall of the receptacle of each assembly and at least one primary keyway in the
plug of the same assembly, each primary key of the receptacle being aligned with a
corresponding primary keyway of the plug of the same assembly, the primary keys and
primary keyways of the connector assemblies having greater numbers of contacts, being
selectively located, relative to the locations of the primary keys and primary keyways
of assemblies having lesser numbers of contacts, to prevent insertion of a relatively
smaller plug having a lesser number of contacts into a relatively larger receptacle
having a greater number of contacts.
[0007] Coded keying of connectors is known, for example from DE-A-2 513 640 and DE-U-2 149
083. It is known from DE-A-616 550 to provide complementary connectors with interengaging
keys and keyways to assist in precluding engagement of a connector having one number
of contact ways with a complementary connector having the same number of ways in ranges
of connectors having different numbers of ways. Some of the connectors are thereby
precluded from engagement with some of the complementary connectors of different numbers
of ways.
[0008] According to the present invention a series of electrical connector assemblies, each
assembly comprising a plug and a 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 endwalls
extending from the mating end to the rearward end, each of the receptacles having
a trough-like plug-receiving opening extending into its mating end, the plug-receiving
opening in each receptacle having opposed sidewalls which are proximate to the external
housing sidewalls and opposed endwalls which are proximate to the external housing
endwalls, the plug of each connector assembly having a forward portion which extends
from its mating end partially towards its 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 in the plug of each assembly and a like plurality of
receptacle contacts in the receptacle of the same assembly, the receptacle contacts
being within the plug receiving opening and being arranged in a row which extends
between the endwalls of the plug receiving opening, the plug contacts of each plug
being proximate to the mating end of the plug and being arranged in a row which extends
between the plug-housing endwalls, the plug-receiving openings of the receptacles
of the series being of increasing width, as measured between the plug opening endwalls,
with increasing numbers of receptacle contacts inthereceptacles, the plugs of the
series similarly being of increasing width, as measured between the plug housing endwalls,
with increasing numbers of plug contacts in the plugs, the height of the plug openings,
as measured between the plug opening sidewalls, being uniform for all receptacles
in the series, the series of electrical connectors is characterised in that plug shields
and receptacle shields are provided on the plugs and the receptacles of the series,
and a keying system is provided comprising at least one keyway on each plug of the
series and one key on each receptacle, the plug shields overlapping the forward portions
of each plug and extending from the forward portions to the rearward portions thereof,
the forward portions having an unshielded section, the keyway being in the unshielded
section, the receptacle shields being on the mating end of each receptacle and extending
into the plug-receiving opening, the key in the receptacle being within the plug receiving
opening and being spaced from the receptacle-shield.
[0009] It is known from DE-U-7 430 223 to provide a coded or polarised connector with a
shielding arrangement.
[0010] The invention will now be described, by way of example, with reference to the accompanying
partly diagrammatic drawings, in which:-
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 diagrammatic views illustrating the principles of the
invention,
Figure 16 is a view similar to Figure 3 showing an alternative embodiment,
Figure 17 is a perspective view of a plug which is intended to be mated with the receptacle
of Figure 16,
Figure 18 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 system and a secondary
keying system. 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 described with reference to Figures 4-15.
[0011] The plug 4 is generally in accordance with the teachings of US 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 endwalls 16. Latch arms
18 extend from the housing endwalls and have rearwardly facing shoulders 19 which
engage shoulders 61 in the receptacle when the plug is mated with the receptacle.
[0012] 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 3 860 316. 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.
[0013] 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 endwalls 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.
[0014] 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.
[0015] Plug-receiving opening 52 has upper and lower sidewalls 56,58 and opposed plug-opening
endwalls 60. The receptacle contacts 62 comprise flat stamped sheet metal members
arranged in side-by-side relationship in a row which extends between the endwalls
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 extend 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.
[0016] 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 US Patent 4 221 458.
[0017] The primary keying system comprising primary keys 78 which are molded integrally
with the upper sidewall 56 of the plug-opening 52. 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.
[0018] The corresponding primary keyways 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.
[0019] As shown in Figure 3, secondary keys 86 are provided on the upper sidewall 56 of
the plug opening 52 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 keyways 88 in the
plug are coextensive with the primary keyways 84 and are of reduced width as compared
with the primary keyways.
[0020] 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 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.
[0021] The darkened rectangles 89 in Figures 4-15 represent the locations of the primary
keys 78 in the receptacles or the primary keyways 84 in the plugs. The smaller undarkened
squares 90 represent the possible sites for secondary keys 86 or secondary keyways
88. It is possible to provide two secondary key sites on the lower sidewall 58 of
the receptacle and corresponding keyways on the lower housing sidewall 14 of the plug
as shown at 92.
[0022] 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 lesser number by virtue of the
locations of the primary keys in the larger receptacle and the absence of keyways
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
connector assembly does not require a primary key and keyway.
[0023] 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 keyway sites 90,92 in
the receptacle and a corresponding keyway is provided in the plug. It will be noted
that the secondary key and keyway sites 90,92 have a width which is only about one-half
that of the width of the primary keys and keyways. It follows that there is no possibility
that a secondary keyway 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.
[0024] The relatively large number of potential sites for secondary keys and keyways provides
the capability of a large number of unique combinations of secondary keys and keyways
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 keyways sites 90,92 has been
limited to ten such sites. In the larger size connector, additional secondary key
and keyway sites could be provided as desired with a resulting increase in the number
of unique or specific keying combinations.
[0025] The primary and secondary keying systems of the invention can be 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 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 the direction of movement
of the mold parts. The primary and secondary keys and keyways 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 keyways. The core
pins which form the primary keys and keyways would ordinarily remain permanently in
the mold parts.
[0026] Figures 16 and 17 show an alternative embodiment in which a primary 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 keyway and the secondary keyway. 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 keyways 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.
[0027] 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.
[0028] 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.
[0029] The plug shield 98 is of sheet metal and has an upper sidewall 106, a lower sidewall
108, and oppositely facing endwalls 110 which are against the corresponding sidewalls
and endwalls 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 116 which is maintained in contact with the shielding material 102 by the locking
member 26. 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 shield.
[0030] 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.
[0031] 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.
[0032] 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 possibility of radiation from the conductors and
contacts.
[0033] 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 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 keyways 84,88
will cooperate with the keys to achieve the keying effects described above.
1. A series of electrical connector assemblies (2), each assembly comprising a plug
(4) and a receptacle (6), each plug (4) "and each receptacle (6) comprising a molded
insulating housing having a mating end (8,34) and a rearward end (10,36) and having
oppositely facing external housing sidewalls (12,14,38,40) and oppositely facing external
housing endwalls (16,42) extending from the mating end to the rearward end, each of
the receptacles (6) having a trough-like plug-receiving opening (52) extending into
its mating end (34), the plug-receiving opening (52) in each receptacle having opposed
sidewalls (56,58) which are proximate to the external housing sidewalls (38,40) and
opposed endwalls (60) which are proximate to the external housing endwalls (42), the
plug (4) of each connector assembly having a forward portion (54) which extends from
its mating end (8) partially towards its rearward end (10) and which is dimensioned
to be received in the plug-receiving opening(52) of the receptacle (6) of the same
assembly, a plurality of plug contacts (30) in the plug (4) of each assembly and a
like plurality of receptacle contacts (62) in the receptacle (6) of the same assembly,
the receptacle contacts (62) being within the plug receiving opening (52) and being
arranged in a row which extends between the endwalls (60) of the plug receiving opening,
the plug contacts (30) of each plug (4) being proximate to the mating end (8) of the
plug and being arranged in a row which extends between the plug-housing endwalls (16),
the plug-receiving openings (52) of the receptacles (6) of the series being of increasing
width, as measured between the plug opening endwalls (60), with increasing numbers
of receptacle contacts (62) in the receptacles, the plugs(4) of the series similarly
being of increasing width, as measured between the plug housing endwalls (16), with
increasing numbers of plug contacts (30) in the plugs, the height of the plug openings
(52), as measured between the plug opening sidewalls (56,58), being uniform for all
receptacles (6) in the series, the series of electrical connectors being characterised
in that plug shields (98) and receptacle shields(100) are provided on the plugs (4)
and the receptacles (6) of the series, and a keying system is provided comprising
at least one keyway (84,88) on each plug (4) of the series and one key (82) on each
receptacle (6), the plug shields (98) overlapping the forward portions of each plug
(4) and extending from the forward portions to the rearward portions thereof, the
forward portions having an unshielded section (54), the keyway (84,88) being in the
unshielded section (54), the receptacle shields (100) being on the mating end of each
receptacle (6) and extending into the plug-receiving opening (52), the key (82) in
the receptacle being within the plug receiving opening (52) and being spaced from
the receptacle shield (100).
2. A series of electrical connector assemblies (2) as set forth in claim 1 characterised
in that the receptacle shield (100) of each receptacle of the series is of stamped
and formed sheet metal, the shield contact portions being cantilever springs (130)
which are integral with the receptacle shield (100) and which extend diagonally into
the plug-receiving opening 52).
3. A series of electrical connector assemblies (2) as set forth in claim 2 characterised
in that the keying system comprises at least one primary key (78) integrally molded
on one of the plug opening sidewalls (56) of each receptacle and a primary keyway
(84) in the corresponding plug external sidewalls (12), the primary keys (78) and
keyways (84) functioning to prevent insertion of a smaller size plug (4) into a larger
size receptacle (6).
4. A series of electrical connector assemblies (2) as set forth in claim 3 characterised
in that the keying system comprises at least one secondary key (86) integrally molded
on one of the sidewalls of each receptacle plug opening (52) and at least one secondary
keyway (88) in the corresponding plug external sidewalls, the secondary keys and keyways
functioning to key a specific plug to a specific receptacle.