Note: Descriptions are shown in the official language in which they were submitted.
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MULTI-CONDUCTOR PLUG AND SOCKET
APPARATUS
Field of the Invention
This invention relates to electrical connections, and more particularly
electrical connections that are electrically activated only when such
connections are fully and appropriately engaged. The invention is specifically
useful when the electrical connections are in the form of coaxial, fixed
diameter, multi-contact mating plug and socket means.
Background of the Invention and Description of the Prior Art
In certain applications it is necessary to connect two active (powered)
electrical circuits together, typically by using a coaxial plug and socket
connectors, each having mating diameters and with multiple circumferential
mating spaced apart electrical contacts.
The procedure of engaging a multiple coaxial plug within a coaxial
socket aperture so as to form the electrical connection with the multiple
2o electrical contacts thereon will cause many of the contacts in the plug to
"wipe"
past those of the socket during insertion, generally in an electrically
inappropriate manner, and may damage the electronic circuits associated with
such contacts before the contacts are each fully and appropriately engaged
with
the corresponding electrical contact. In addition, a further problem arises in
that the preferred method of making such electrical connections is typically
to
insert by rotationally screwing one tubular housing containing the plug into a
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similar tubular housing containing the socket. The environment in which this
occurs could also be hazardous - for instance, on the floor of an oil-drilling
rig
where flammable gases may be present. In such circumstances it is advisable to
make certain that no potentially live electrical contacts are capable of
causing a
spark or thermal effect that could ignite flammable gas, dust or vapor during
rotatable insertion of the plug into the socket.
Still further problems exist with the hazardous environment in which
such plus-socket connectors may be exposed. For example, drilling strings used
1o in the oil industry require insertion therein of electronic monitoring and
transmitting devices to allow drill operators to monitor various drilling
parameters at the base of the well bore during drilling operations. Electronic
devices which fit within the inner diameter of drill pipe of a drill string
are
typically cylindrical devices consisting of sensors, telemetry apparatus and
batteries or power supplies, that together on average are less than 2 inches
in
diameter, and when connected can be 30 feet long. Such devices typically
comprise specific pressure housings that require mechanical and electrical
interconnections (contacts). These connection points are particularly
vulnerable
to severe shock and vibration, bending, compression and tension, high
pressures
2o and high fluid flow rates in the very harsh downhole-drilling environment.
Various methods have been developed and used in the industry to join,
both mechanically and electrically, components of such electronic devices
together in order to cope with the conditions of a drilling environment. The
majority of these devices comprise a multi-contact plug and socket that cannot
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be rotated one into the other. Such connectors are firstly joined in a
specified
fashion and are then typically protected by a mechanical housing able to
resist
the downhole pressure. Many problems arise from the relatively complicated
connection procedures necessary to connect such tool modules together, since
not only must the longitudinal positioning of the two components be aligned
but
also they must be aligned properly in the angular sense relative to each
other.
A simplification in the connection process that allows a more robust and
reliable connection to exist utilizes a coaxial barrel style plug and socket
design.
1 o Such design enables the plug to be attached to a housing, the socket
attached to
a similar housing and the pair are then simply pushed or screwed one into the
other. Significant advantages that follow from the use of such a system are
that
smooth barrel joints are easily implemented, thereby minimizing flow erosion;
mechanical complexity is reduced leading to more reliable systems and cost-
effective implementations; and tool modules themselves can be housed in larger
drill collars, enabling a simplification of the process whereby 'collar plus
tool'
is attached to another 'collar plus tool'.
One prior art design that is economical, basic and reliable involves a
2o coaxial barrel style plug and socket having a single diameter. Such design
would otherwise be the connector system of choice were it not for the
following
problems, namely, that when fully engaging a single diameter plug and socket
many of the contact rings slide past each other. In a connection system of
more
than two contact rings (and hence more than two electrical lines) that may be
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electrically active, there is a danger that misappropriate or unsafe
connections
may be made thereby damaging associated electronic circuits.
A known prior-art method and configuration to avoid the above problem
of "wiping" causing inappropriate electrical connection is to modify the
spacing
of the contacts on the plug and socket pair such that no more than a single
contact is able to make contact with another before engagement. This method,
and a plug and socket combination employing such a configuration, is taught in
Patent US 6,439,932. The aforesaid method and configuration has the serious
disadvantage that in order the ensure no more than one contact connection is
allowed at any time prior to full engagement, the inter-contact spacings have
to
be implemented at increasingly large distances from each other. This leads to
a
costly, long and unwieldy plug and socket pair, particularly when more than
six
independent connections have to be made. For instance, a mathematical
analysis will show that such a connector is more than twice the length of a
normal coaxial connector implemented with uniform spacing.
A plethora of alternative schemes that use switching means that
electrically isolate connections until the appropriate electrical connections
are
2o fully made and thus avoid the wiping problem are discussed below.
US Patent 6,528,746 shows a non-coaxial connector means that uses a
magnet to activate a magnetic flux responsive device (typically a reed switch)
that then enables connections to be made.
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US Patent 5,048,914 shows a non-coaxial connector that uses an optical
transmitter/receiver pair to activate its switches.
US Patent 5,580,261 teaches a means for connecting a single pair of
coaxial contacts which relies on the mechanical motion of an internal switch,
the switch means ultimately causing a mechanical connection of the contacts.
This invention is typical of the class of mechanical movement initiating
further
connections.
to Another class of mechanical switches is the subject of many inventions
that rely on solid-state switches (electronic switches) to control further
switched
connections. US 4,346,419 is an example of this area of prior art. It
specifically teaches the use of non-coaxial contacts of differing lengths, a
short
pair (last to connect) that when connected enables a solid-state switch to
pass
relatively high current through other longer pairs of longer contacts.
Disadvantageously, this design requires the last contact to be continuously
supplied with a voltage. Accordingly, despite low "trigger" voltages being
used, such configuration is nonetheless unsatisfactory in explosive
environments due to the possibility of initiating an explosion.
Typical of modern coaxial connectors is the invention as shown in
Patent US 6,435,917. This teaches an improved manner of maintaining a
reliable connection specifically related to socket contacts. However, such
design provides no protection against inappropriate connections being made
when engaging plug into socket.
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US 5,984,687 and US 5,409,403 are typical of rotatable coaxial
connector patents. These examples teach the use in specific circumstances of
placing each successive contact on a successively increasing diameter. The
essential advantages of this class of design are that all contacts are made
only
when plug and socket are essentially fully engaged, and that plug and socket
can rotate about a common axis. The disadvantages are that such devices are
relatively expensive and usually require a significantly larger diameter
implementation than a simple fixed diameter coaxial multi-contact plug and
1o socket, such as is specified in the present invention. Furthermore, there
is no
means by which such devices alone could safely operate in an explosive or
hazardous environment.
In conclusion, the prior art teaches the use of plugs and sockets in
rotatable (coaxial) and non-rotatable forms that enable contacts to connect
when
a fully engaged position between plug and socket is achieved. The
determination of this position is implemented via one or more of the
following,
namely:
contact axial spacing differences;
contact diameter spacing differences;
mechanical movement of a probe enabling contacts to be connected;
optical switch; and,
a magnetic switch.
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While these above prior art designs exist, there is a real need, however,
for a plug and socket design which combines a number of features, namely:
comparatively small in footprint;
avoids the "wiping" problem;
simple mechanical housing;
can operate in hazardous environments; and
relatively inexpensive relative to some of the prior art designs.
SUMMARY OF THE INVENTION
1o Our invention enables a mufti-contact coaxial plug to be axially inserted
into its partner socket while electronic circuits attached to either side of
the plug
and/or socket are isolated from any harmful electronic misalignment during the
engagement procedure. The plug and socket do not require any particular
contact spacing and so can be realized in the smallest appropriate volume i.e.
small fixed diameter and short fixed contact spacings.
Accordingly, the invention, in one of its broad aspects, contemplates a
very simple basic electrical diode attached to the plug, enabling a sensor
circuit
attached to the socket to activate various solid state switches to protect the
2o socket's attached electronic circuitry and permit electrical supply of
power only
when the plug and socket combination are fully engaged, and a similar standard
electrical diode attached to the socket enabling a similar sensor circuit
attached
to the plug to activate various solid state switches to protect the plug's
attached
electronic circuitry also only when the plug and socket combination are fully
engaged. The sensor circuits are symmetric and allow the protection means to
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activate when either the plug's circuit only is implemented, when the socket's
circuit only is implemented, or when both are implemented. A specific
embodiment facilitates this activation for both circuits when either or both
are
electrically powered.
A specific advantage of our invention is that such electrical connections
and disconnections can be safely undertaken in hazardous environments.
Specifically, the present invention in one of its broad embodiments
1o comprises a multiconductor plug and socket means;
said plug means having at least three electrically
conducting plug contacts thereon, adapted for insertion in socket
means;
said socket means having a corresponding number of
electrically conductive socket contacts thereon;
a first of said plug contacts electrically coupled to a
second of said plug contacts via a plug-side current direction-
limiting means ;
a first of said socket contacts electrically coupled to a
2o second of said socket contacts via a socket-side current
direction-limiting means;
said first and second plug contacts adapted for electrical
communication with said first and second socket contacts only
upon proper engagement of said socket means with said plug
means; and
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circuit isolation means, said circuit isolation means only
permitting flow of electrical current through one or more
remaining plug-socket contact pairs when current flow through
at least one of said plug-side and socket-side current direction-
limiting means is detected.
'The current direction-limiting device referred to above is typically a
diode, but may be any combination of electrical or electronic circuits capable
of
providing this functionality.
In one refinement of the present invention, the circuit isolation means
comprises plug-side circuit isolation means, said plug-side circuit isolation
means only permitting flow of electrical current to at least one remaining
plug
contact when current flow through said socket-side current direction-limiting
means is detected.
In an alternative refinement of the present invention, the circuit isolation
means comprises socket-side circuit isolation means, said socket-side circuit
isolation means only permitting flow of electrical current to at least one
remaining plug contact when current flow through said plug-side current
direction-limiting means is detected.
In a further refinement of the invention, where circuit isolation means is
desired to prevent unintended shorting to electronic circuits on both the plug
side and socket side of the electrical connection, the circuit isolation means
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comprises both plug side circuit isolation means and socket side circuit
isolation
means, both functioning as described above.
A timing circuit preferentially forms part of the circuit isolation circuit,
and
includes a delay from the time of connection between the plug means and
socket means during which time electrical connection between the contacts
must be fully established. One advantage of a timing circuit is that such a
time
delay prevents premature or intermittent contact associated with the current
direction limiting means (typically a diode) from consequently triggering the
establishment of electrical power to one or both of the plug contacts or
socket
contacts before full engagement of the plug means within socket means has
been obtained.
In yet a further broad aspect of the present invention, the present invention
comprises an apparatus for establishing electrical connection between a pair
of
electrical contacts, comprising
plug means;
socket means;
said plug means having one of said pair of electrical
contacts thereon and a further first and second electrical plug
contact thereon, said plug means adapted for insertion in said
socket means;
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said socket means having the other of said pair of
electrical contacts thereon, and a further first and second socket
contact thereon;
said first of said plug contacts electrically coupled to
said second of said plug contacts via a plug-side current
direction-limiting means;
1 o said first socket contact electrically coupled to said
second of said socket contacts via a socket-side current
direction-limiting means;
said first and second plug contacts adapted for electrical
communication with said first and second socket contacts only
upon proper engagement of said socket means with said plug
means; and
circuit isolation means, said circuit isolation means only
permitting flow of electrical current through said pair of
electrical contacts when current flow is detected through at least
one of said plug-side and socket-side current direction-limiting
means.
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BRIEF DESCRIPTION OF THE DRAWINGS
The following drawings, showing preferred embodiments of the
invention, are illustrative only, and for a complete definition of the scope
of the
invention, reference is to be had to the summary of the invention and the
claims.
l0 Figure 1 is a schematic showing a generalized form of the coaxial plug
and socket connection of the present invention;
Figure 2 is a more detailed schematic diagram of the isolation circuit
for the plug isolating electronic switch circuit shown in Figure 1;
Figure 3 is a more detailed schematic diagram of the isolation circuit
for the socket side isolating electronic switch circuit shown in Figure 1;
Figure 4 shows schematically a sensor circuit of the type used in the
isolation circuits shown in Figure l, where both plug and socket have
associated
circuits and are each electrically powered;
Figure 5 is a sensor circuit similar to that shown in Figure 4, but
modified slightly to form an alternate embodiment;
Figure 6 shows schematically a sensor circuit, where only the plug side
has associated isolation circuits and is electrically powered;
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Figure 7 shows schematically a sensor circuit, where only the socket
side has associated circuits and is electrically powered; and,
Figure 8 is a schematic drawing showing a typical plug and socket
connector which may be used in the present invention, indicating wiring
connections that corresponds to the associated wiring of the respective plug
and
socket electrical isolation circuits.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
While there are many methods of connecting two electronic circuits
together, in one aspect the invention contemplates use of a coaxial plug and
socket pair 212 and 226 respectively, as indicated in Figure 1, each having a
plurality of coaxially situate, concentric electrical contacts 211, 213
respectively thereon. The advantage of using such a coaxial mufti-contact
system is that the plug 212 and socket 226 can be housed in tubular containers
(not shown) and the containers may be screwed together, thereby engaging the
coaxial plug 212 into socket 226. The mechanical advantage of this method of
engagement brings a disadvantage - the majority of the contacts 211, 213 wipe
past each other during insertion of plug 212 into socket 226 before the plug
212
and socket 226 become fully engaged. This may cause damage to attached
electronic components if they are activated by some power source.
Accordingly, the invention provides for interposing specific isolation
circuits
202 and/or 216 to isolate and protect such components during the engagement
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process. We accomplish this by connecting plug 212 via wire harness 210 to
switching circuit 202. This circuit 202 isolates a variety of input/output
lines
(I/O) 200 from I/O lines 208. A pair of lines is dedicated to use as sensor
lines
(Sensor Line 1 280 and Sensor Line 2 282) and are attached to contacts 284 and
286 which are preferably but not necessarily at the distal end 207 of plug
212.
Similarly we connect socket 226 via wire harness 224 to an isolation circuit
216. Circuit 216 isolates a variety of input/output lines (I/O) 214 from I/O
lines
222. A pair of lines is dedicated for use as sensor lines (Sensor Line 1 292
and
Sensor Line 2 294) and are attached to contacts 288 and 290, which are
1o preferably, but not necessarily at the distal end 221 of socket 226.
For simplicity of deployment we have designed circuit 202 to be
identical to circuit 216 (ref. Figures 2 and 3) though this feature is not a
required aspect of this invention. Although we indicate seven sets of
corresponding electrical contacts associated respectively with plug 212 and
socket 226, it is obvious that the number of sets of contacts applicable to
this
application can be any reasonable number greater than two, and the depiction
of
seven contacts is merely arbitrary and illustrative of the principles to be
employed.
Figure 2 is a more detailed schematic diagram of the isolation circuit
202 in respect of the plug contacts 211, as shown in Figure 1. The I/O lines
comprise a Power Line 235 monitored by Current Sensor 242 that controls
Power Switch 244, Digital Lines 233, 234 controlled by Digital Switches 246,
an Unswitched Line 248, a Ground Line 250, two Sensor Lines 280 and 282
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controlled by Sensor Circuit 256, and Timer Circuit 258, the Timer 258
providing an Interrupt Line 260 to control Power Switch 244 and Digital
Switches 246. A diode 276 is carried by Sensor Lines 280 and 282.
Figure 3 is a more detailed schematic diagram of the isolation circuit
216 in respect of the socket contacts 213, as shown in Figure 1. The I/O lines
comprise a Power Line 236 monitored by Current Sensor 241 that controls
Power Switch 243, Digital Lines 231, 232 controlled by Digital Switches 245,
an Unswitched Line 247, a Ground Line 249, two Sensor Lines 292 and 294
controlled by a Sensor Circuit 257 and Timer Circuit 259, the Timer 259
providing an Interrupt Line 261 to control Power Switch 243 and Digital
Switches 245. A diode 302 is carried by Sensor Lines 292 and 294.
Figure 4 shows plug Sensor Circuit Detection means 263 and socket
Sensor Circuit Detection means 264 shown generally in Figures 2 and 3
respectively and how the Sensor Lines 292, 294 and 280, 282 are activated only
by the full engagement of the plug 212 and socket 226. A positive potential +V
on the plug sensor circuit side 235 is connected to a resistor Rl (272), then
to a
forward-biased diode 274, then to diode 276 that acts to block this current,
and
finally to another resistor R2 (278) that is grounded 250. Sensor Line 1 (280)
2o from the junction of 274 and 276 is connected to plug contact 284. Sensor
Line
2 (282) from the junction of 276 and 278 is connected to plug contact 286 and
also to the plug Sensor Circuit input 256. Similarly, a positive potential +V
on
the socket circuit side 236 is connected to a resistor R1 (298), then to a
forward
biased diode 300, then to a diode 302 that acts to block this current, and
finally
to another resistor R2 (304) which is grounded 250. Sensor Line 1 (292) from
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the junction of 300 and 302 is connected to socket contact 290. Sensor Line 2
(294) from the junction 302 and 304 is connected to socket contact 288 and
also
to the socket Sensor Circuit input 257.
s It will be noted that the sensor lines 292, 294 on the socket Sensor
Circuit Detection means 264 are crossed with respect to socket connections 288
and 290. Apart from this detail the full circuits and wiring for both plug and
socket Sensor Circuits 256, 257 are identical. The plug-side and socket-side
Sensor Circuit Detection means 263, 264 may alternatively be arranged as
to shown in Figure 5, wherein Sensor Lines 280, 282 are crossed with respect
to
plug connections 284 and 286.
We proceed by explaining various embodiments in order to clarify how
the system determines when the plug/socket combination has achieved full
15 engagement.
EMBODIMENT 1
Figure 6 denotes an arrangement where active powered electronic
circuits are incorporated only on the plug side, and furthermore that
electronic
2o access to the plug side circuits does not require socket side isolation
circuitry
because the socket side is essentially passive. For illustrative purposes we
set
the power line +V at 15 volts, resistor R1 (272) is 50,000 ohms and resistor
R2
(278) is 100,000 ohms.
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As may be seen with reference to Figure 6, the determination of the full
engagement of plug 212 and socket 216 (whereby electronic circuitry which
requires isolation occurs on the plug side) is achieved as follows. Current
from
supply line 235 flows through resistor R1 (272), through forward-biased diode
274 and is blocked from the plug sensor circuit output by diode 276. A current
pathway is available across the plug/socket junctions 284 and 288, through
diode 302 that now acts as a sensor activation element by passing current back
through plug/socket junctions 290 and 286, and finally through resistor R2
(278) to Ground 250. The potential across resistor R2 (278) with respect to
l0 Ground 250 is sensed by the plug Sensor Circuit 256 to be approximately 2/3
times 15V (set by the potential divider R1/R2 i.e. ~lOV). The threshold
voltage necessary to activate the plug Sensor Circuit (256) could be set at 6
or 7
volts, greater than typical logic levels of SV. Thus the activation voltage of
~IOV is comfortably greater than the threshold, and false activations are
minimized. Diode 302 is forward biased because of the crossed sensor lines
292 and 294 on the socket side. Were this not the case the required voltage
potential at the plug Sensor Circuit 256 would not be available because no
current could flow through resistor R2 (278), causing the appropriate
activating
voltage to be absent. Thus only when plug 212 and socket 216 are fully
2o engaged is the plug Sensor Circuit 256 activated, and the switched lines
forming part of the I/O bus 200 are then electrically connected to the I/O bus
208. Hence the switched (and also the unswitched) lines are correctly
available
at the socket via the fully engaged plug.
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It will be obvious to one reasonably skilled in the art that there should
be no electrical circuits associated with socket 226 such as Digital Switches
245
that are in electrical communication with any of the non-sensor contacts 213
that would be electrically mistaken for the action of diode 302, so as to
otherwise initiate a "triggering" of the Power Switch 244. To further guard
against such a possibility, in a preferred embodiment of this aspect of the
invention the output of Sensor Circuit 256 in respect of the plug sensor
circuitry
is passed through timer 258 (ref. Figure 2). The function of Timer Circuit 258
is to delay activation of Interrupt Line 260 controlling Power Switch 244 and
Digital Switches 246 until the full engagement of plug 212 and socket 226 can
be reasonably expected (typically one to two minutes).
The only significant requirements on the passive socket side is a diode
302 that is forward biased by crossed sensor lines 292, 294 in order that the
Sensor Circuit 256 is correctly activated.
EMBODIMENT 2
The complementary circuit to Embodiment 1 is depicted in Figure 7
and denotes an arrangement where active powered electronic circuits are
incorporated only on the socket side, and furthermore that electronic access
to
the socket side circuits does not require plug side isolation circuitry
because the
plug side is essentially passive. For illustrative purposes we set the power
line
+V at 15 volts, resistor Rl (298) is 50,000 ohms and resistor R2 (304) is
100,000 ohms.
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As may be seen with reference to Figure 7, the determination of the full
engagement of plug 212 and socket 216 (whereby electronic circuitry which
requires isolation occurs on the plug side) is achieved as follows. Current
from
supply line 236 flows through resistor R1 (298), through forward-biased diode
300 and is blocked from the plug sensor circuit output by diode 302. A current
pathway is available across the plug/socket junctions 290 and 286, through
diode 276 that now acts as a sensor activation element by passing current back
through plug/socket junctions 284 and 288, and finally through resistor R2
(304) to Ground 250. The potential across resistor R2 (304) with respect to
Ground 250 is sensed by the socket Sensor Circuit 257 to be approximately 2/3
times 15V (set by the potential divider R1/R2 i.e. ~IOV). The threshold
voltage necessary to activate the socket Sensor Circuit (257) could be set at
6 or
7 volts, greater than typical logic levels of SV. Thus the activation voltage
of
~IOV is comfortably greater than the threshold, and false activations are
minimized. Diode 276 is forward biased because of the crossed Sensor Lines
292 and 294 on the socket side. Were this not the case the required voltage
potential at the socket Sensor Circuit 257 would not be available because no
current could flow through resistor R2 (304), causing the appropriate
activating
voltage to be absent. Thus only when plug 212 and socket 2i6 are fully
2o engaged is the socket Sensor Circuit 257 activated, and the switched lines
forming part of the I/O bus 214 are then electrically connected to the I/O bus
222. Hence the switched (and also the unswitched) lines are correctly
available
at the socket via the fully engaged plug.
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It will be obvious to one reasonably skilled in the art that there should
be no electrical circuits associated with plug 216 such as Digital Switches
246
that are in electrical communication with any of the non-sensor contacts 213
that would be electrically mistaken for the action of diode 276, so as to
otherwise initiate a "triggering" of the Power Switch 243. To further guard
against such a possibility, in a preferred embodiment of this aspect of the
invention the output of Sensor Circuit 257 in respect of the socket sensor
circuitry is passed through timer 259 (ref. Figure 3). The function of Timer
Circuit 257 is to delay activation of Interrupt Line 261 controlling Power
to Switch 243 and Digital Switches 245 until the full engagement of plug 212
and
socket 226 can be reasonably expected (typically one to two minutes).
The only significant requirements on the passive plug side is a diode
276 that is forward biased by crossed sensor lines 292, 294 in order that the
Sensor Circuit 257 is correctly activated.
EMBODIMENT 3
The discussion of Embodiment l and Embodiment 2 above now makes
the complete understanding of Embodiment 3 as exemplified by either Figure 4
or Figure 5 straightforward. Both plug sensor circuit 236 and socket sensor
circuits 264 are powered independently by +V(plug) 235 and +V(socket) 236
lines. Taking Figure 4 for example, the voltage level output to Sensor Circuit
256 (plug) is available via either of two routes:
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a) current from line 235 via resistor Rl (272) and diode 274 passes along
Sensor Line 1 (280) to contacts 284 and 288, then via Sensor Line 2 (294)
through diode 302, Sensor Line 1 (292), contacts 290 and 286, Sensor Line 2
(282) and through resistor R2 (278) to Ground 250. The potential at the
junction of R2 (278) and Sensor Line 2 (282) with respect to Ground 250 is
now available to activate the plug Sensor Circuit 256; or
b) current from line 236 through resistor Rl (298) and diode 300 passes
along Sensor Line 1 (292), through contacts 290 and 286, then via Sensor Line
2 (282) through resistor R2 (278) to Ground 250. The potential at the junction
of R2 (278) and Sensor Line 2 (282) with respect to Ground 250 is now
available to activate the plug Sensor Circuit 256.
The choice of routes a) or b) is determined solely by whether +V(plug)
235 is greater than +V(socket) 236 by more than one diode drop (typically
0.6V). In either case the significant issue is that the plug Sensor Circuit
256 is
activated by an adequate +V(socket) 236 potential or by the presence of diode
302 - both are associated only with the full engagement of the plug and
socket,
and either will suffice.
Likewise, the voltage level output to Sensor Circuit 257 (socket) is
similarly available via either of two routes:
c) current from line 236 via resistor R1 (298) and diode 300 passes along
Sensor Line 1 (292) to contacts 290 and 286, then via Sensor Line 2 (282)
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through diode 276, Sensor Line 1 (280), contacts 284 and 288, Sensor Line 2
(294) and through resistor R2 (304) to Ground 250. The potential at the
junction of R2 (304) and Sensor Line 2 (294) with respect to Ground 250 is
now available to activate the plug Sensor Circuit 257; or
d) current from line 235 through resistor Rl (272) and diode 274 passes
along Sensor Line 1 (280), through contacts 284 and 288, then via Sensor Line
2 (294) through resistor R2 (304) to Ground 250. The potential at the junction
of R2 (304) and Sensor Line 2 (294) with respect to Ground 250 is now
to available to activate the plug Sensor Circuit 257.
Again, the choice of routes c) or d) is determined solely by whether
+V(socket) 236 is greater than +V(plug) 235 by more than one diode drop
(typically 0.6V). In either case the significant issue is that the socket
Sensor
Circuit 257 is activated by an adequate +V(plug) 235 potential or by the
presence of diode 276 - both are associated with the full engagement of the
plug and socket, and either will suffice.
Diodes 274 and 300 ensure that there can be no unintended reverse
2o current flow into their associated power supply from the power supply at
higher
potential on the other side of the plug/socket.
This embodiment illustrates usefulness of the symmetry of the circuit
operations attached to either plug or socket - fabrication of the switching
circuits is simplified in that both assemblies can be identical. The only
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necessary modification is that the lines must be crossed between contacts 288,
290 and Sensor Lines 292 and 294 (as shown in Figure 4), or equally between
contacts 284, 286 and Sensor Lines 280 and 282 (as shown in Figure 5). In
these embodiments, when plug and socket are fully engaged, Figures 2 and 3
indicate that the Power Switch lines (235, 236), Digital Switch lines (233,
234,
231, 232), the Unswitched Lines, Ground Lines and Sensor Lines are all
connected appropriately. This enables power to flow as required from plug to
socket or vice versa, digital information to flow as required from plug to
socket
or vice versa, etc.
to
Our invention does not limit us to a 'one-to-one' line connection
correspondence, however. The obvious inclusion of more contacts in plug 212
and socket 226 would enable the independence of the information or power
carrying lines. The necessary and sufficient feature for determining full
engagement is that plug Sensor Line 1 (280) connects to socket Sensor Line 2
(294) and plug Sensor Line 2 (282) connects to socket Sensor Line 1 (292)
when diode 276 and/or diode 302 (for example) are chosen as the engagement
sensing devices. Specific wiring connections through a representative plug and
socket pair is depicted in Figure 8. In particular the Sensor Line crossed
wiring
(282 to 292, 280 to 294) is evident.
Importantly, with respect to each of the embodiments shown in Figures
2 and 3, the present invention is not limited to a sensory circuit using only
a
simple diode as a sensing means. In particular, it is possible and is
contemplated
within the scope of the present invention to replace each diode 276 and/or 302
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CA 02440779 2003-09-05
by other electrical circuitry, including current direction-limiting circuitry,
so as
to permit the sensor circuit to produce a particular electronic signal when
specifically sensed at full engagement of the plug 212 and socket 226. The
present invention is not to be limited to circuitry implementing only diodes
276
and 302.
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