Electronically actuated retaining latch for AC-DC adapter removable plug assembly

A power adapter has a solenoid actuated retaining latch controlled by an electronic circuit that detects the presence or absence of AC mains voltage. When the assembled AC-DC adapter and plug assembly are removed from the wall, the latch detects removal and unlocks the plug assembly for easy removal without undue force required by the user. The circuit is designed for minimal power consumption, and the solenoid only consumes power when it is engaging or disengaging the latch.

CROSS-REFERENCE TO RELATED APPLICATIONS

FIELD

The example technology herein relates to international power adapters, and more particularly to power devices that can be reconfigured for different power mains socket types.

BACKGROUND & SUMMARY

While the world long ago agreed on alternating (not direct) current (AC) for electrical “mains” (household) power delivery, there is no worldwide standardization on the configuration of AC connecting plugs or even AC voltages and frequencies. North America generally uses 110 VAC at 60 Hz, Japan uses 100 VAC at 50 or 60 Hz (depending on which part of the country you are in) and most of Europe uses 230 VAC at 50 Hz. Moreover, there are at least twelve different types of AC electrical plugs in widespread use throughout the world. North America and Japan settled on Types A (two-prong ungrounded) and B (three-prong grounded), whereas most of South America, Africa, Europe and Asia use Type C. Parts of Africa and parts of Asia use Type D, a smattering of countries in Europe, Asia and Africa use Types E, F, G and H, Australia and some businesses in Japan use Type I, Liechtenstein uses type J, and so on. None of these are compatible with one another, requiring worldwide travelers to bring along plug adapters to enable them to plug their AC devices into AC mains outlets of different countries. See www.trade.gov/mas/ian/ECW/characteristics.html.

Many modern digital appliances such as computers, tablets, smart phones and the like operate at voltages lower than the power mains, such as 5 VDC or 12 VDC. Such appliances often employ an external “power adapter” (step-down transformer or other circuit) to step the AC mains line voltage down to the particular lower voltage the appliance requires. Some such power adapters rectify the stepped-down voltage to convert alternating current from the power mains to direct current. These power adapters are often called “AC-DC power adapters.”

To accommodate these various different worldwide power conventions, it is common practice to design such AC-DC power adapters with removable plug assemblies. This is beneficial to the manufacturer because it enables a single power adapter to be sold globally by shipping it with the specific plug assemblies required for each particular region. In some cases, the manufacturer provides several different interchangeable removable plug assemblies to the end user so the end user can use the same adapter in different global regions just by swapping between interchangeable plug assemblies. Users benefit by having a means of making the adapter compatible with different types of receptacles while traveling.

Some such interchangeable plug assemblies rely either on friction or a mechanical latch to retain the plug assembly in the body of the main adapter. These retaining systems can be confusing to the user, because without instructions printed on the device, it is not always clear which direction to pull or how much force to apply to the latch in order to disengage the plug assembly from the adapter body.

As a separate problem, AC-DC adapters which have the orientation of the AC prongs fixed relative to the adapter body will inevitably block an adjacent AC mains outlet depending on orientation of adjacent outlets in a power strip or wall socket. Some earlier solutions provided for rotation of the AC mains blades, but in such solutions the rotating blade mechanism is generally not detachable from the AC adapter body.

Further improvements are possible.

DETAILED DESCRIPTION OF NON-LIMITING EXAMPLE EMBODIMENTS

Example non-limiting embodiments herein replace the mechanically actuated retaining latch of a power adapter with a solenoid-actuated retaining latch. This solenoid is controlled by an electronic circuit that detects the presence or absence of the AC mains voltage. When the assembled AC-DC adapter and plug assembly are removed from the wall socket, the latch detects removal and unlocks the plug assembly for easy removal without undue force required by the user. The circuit is designed for minimal power consumption, and the solenoid consumes power only when it is engaging or disengaging the latch.

With such example non-limiting embodiments, it is possible to design the plug assembly such that it is held temporarily to the main AC-DC adapter body with a light and precise force. This light force could be implemented with permanent magnets or some other material that would provide the desired feel to the user. Once the unit is inserted into the wall, the electromagnetic latch engages with the necessary force required by the user to insert the plug assembly from the force required by the power adapter to retain it. In other words, some example non-limiting embodiments decouple the force required by the user to insert the plug assembly from the force required by the power adapter to retain it. The user experience of the insertion and extraction of the plug assembly can then be independently customizable. This enables a novel user experience.

Other aspects of disclosed non-limiting embodiments address the problem of blocked outlets by providing a detachable regional adapter which be installed in multiple orientations to prevent the body of the adapter from blocking adjacent outlets. Novel aspects include the shape and orientation of the electrical contacts between the regional adapter and the main AC adapter body, which allow for multiple orientations while still meeting international safety standards. The latching mechanism safely holds the regional adapter to the AC adapter body, and the magnetic alignment features aid in user installation of the regional adapter.

Such example non-limiting embodiments provide the ability install the regional adapter in multiple orientations relative to the AC adapter body. This provides streamlined logistics for international distribution by separating the regional differentiating features from the common features of the adapter.

Additional example non-limiting features and advantages include:Clip inside to provide a “Click” feel while prong foldingTerminal feature made to be flexible to smoothly contact with prongsLatch Pin reinforced (e.g., with a reinforcing steel or other rigid pin inserted into the tool and co-molded within the Latch Pin) so that it can withstand abuse without breakingpart/assembly tolerances (e.g., the distance from the bottom of the assembly to the pin/latch contact point, and the distance from the top of the Adapter Face to the pin/latch contact point) controlled for solid latching experiencePin/Latch tolerance loop shortened e.g., by merging latch pin and associated faceBottom face of assembly provides the required point of adapter contact to limit the tolerances that impact the Pin<->latch connection (e.g., the outer cover frame face is the datum for contact; Target=PIN/FACE will be USW to DH held flush cover to 0.10 proud of the Cover lip; the Outer Cover Frame is not the first point of contact no matter how the user tries to make the coupling)Merging of the latch pin and the face, and using the bottom face to locate means the outer cover will only contact the plastic face of adapter along one edge; a single critical tolerance is controlled to assure good latching; the bottom face is the only point of contact on all four sides since locating on both the Face and the Cover could result in tilt and create a gap; the cover will not contact the adapter face on three sides (on the other 3 sides the face controls contact).Design of the Adapter Face assembly controls the tolerance and assembly loop to assure good Pin<->Latch connection.

FIG. 1shows an example non-limiting kit100useful for adapting a power mains to an electrical or electronic appliance. In the example shown, kit100comprises an adapter base102and a plurality of interchangeable plug connectors104(1),104(2) . . .104(N). In the non-limiting example shown, kit100includes the following components:a Type C plug connector104(1) (which can be used in most of continental Europe, Asia, South America and Africa);a Type G plug connector104(2) (which can be used in China, India, the United Kingdom, parts of Africa and South America, and parts of Southeast Asia);a Type A plug connector104(3) (which can be used in the United States, Japan, central America, parts of South America, parts of Africa, and parts of Southeast Asia);an ungrounded Type H plug connector104(N) (which can be used in China, parts of Africa, parts of Central and South America; andthe adapter base102.

Power prongs104are interchangeably connectable to the adapter base102—one at a time—to assemble any number of differently-configured integrated adapters108. The kit100can contain any number of plug connectors104(that is, “N” can be any positive integer). The plug Types shown are exemplary. Any plug Type is possible.

Plug connectors104have extending power prongs110that are used to electrically connect to power mains. These power prongs110are typically made of a conductive metal such as brass or nickel-plated brass. The power prongs conduct AC voltage and current from the power mains to the adapter base102when the power prongs are inserted into corresponding female socket portions of the power mains. The number of power prongs110depend on the Type of female socket they are designed to be compatible with. There will typically be at least two (2) prongs110on each plug connector104(two AC lines), and some plug connectors (e.g., plug connector104(2) have three prongs (two line voltages and one ground).

In the non-limiting examples shown, each of plug connectors104provides a male plug configured to mate with a female mains power socket (generally, mains power sockets are female so that there is no protruding portion that could be accidentally contacted to deliver an electric shock). However, other configurations are possible. For example, in low voltage applications where the risk of shock is reduced or eliminated, the interchangeable plug connectors104could be female sockets or have both male portions and female portions.

To use kit100, the user selects one of plug connectors104(this selection is typically made based on the type of power mains socket or other connector the user wants to connect to). The user then mates the selected plug connector104with the adapter base102to form an integrated power adapter108. When the user wishes to make the adapter108compatible with a different type of power mains socket or other connector, the user removes the plug connector104currently mated with the adapter base102and replaces it with a different plug connector104selected to be compatible with the different power mains socket type. Thus, any one of plug connectors104can be removably, physically and electrically connected to the adapter base104to form an integrated adapter compatible with a certain power mains configuration (seeFIGS. 2A, 2Bfor the example where plug connector104(3) is connected to the adapter portion). The adapter base102can be reused with different plug connectors104to provide a differently-configured integrated adapter108that is compatible with differently-configured power mains.

As will be explained in more detail below, the example non-limiting embodiments provide improvements so that adapter base102automatically firmly retains the selected plug connector104so long as the integrated adapter108is plugged into the power mains yet allows the user to easily remove and replace plug connectors from/to the adapter base when the adapter is unconnected from the power mains.

Adapter Base Housing Shape

In the particular non-limiting example shown, the adapter base104is generally rectangular with a cutout106dimensioned and shaped to physically accommodate (one at a time) each of plug connectors104. In particular, the plug connectors104each are shaped to fit into the cutout106of adapter102so that when a given plug connector104is physically mated with the adapter base102, the plug connector conforms with the shape of the adapter base102and the resulting assembled adapter108form factor (as shown inFIGS. 2A, 2B) resembles an integral whole (e.g., a rectangular or cubic block) with no extending portions other than power prongs110. As can be seen inFIGS. 2A and 2B, some power prongs110,110′ can be retractable between a retracted position (FIG. 2A) and an extended position (FIG. 2B) so that the prongs can be retracted when not in use to make the integrated adapter108more compact for storage and more aesthetically pleasing. Shapes such as rectangular and cubic for the integrated adapter108are non-limiting. Any desired shape is possible including for example D-shaped, circular, oblong, spherical, rod-shaped or any other desired shape.

Removably Latching Interchangeable Plug Connectors Into Adapter Base

FIG. 1shows that adapter base102includes, positioned within cutout portion106, a protruding latching receptacle112including a recess114dimensioned, shaped and configured to accept and retain a latch pin116extending from a(ny) plug connector104. In the non-limiting example shown, every plug connector104has a similarly-configured or identically-configured latch pin116so that each or any plug connector latching receptacle112can mate with the common adapter base102. In the example shown, the adapter base protruding latching receptacle112is capable of selectively firmly retaining/latching a latch pin116and selectively fixedly mechanically and electrically attaching/connecting the associated plug connector104to the adapter base102.

Latching in Multiple Different Orientations

In example non-limiting embodiments, latching pin116is symmetrical such that it can mate with latching receptacle112in any of plural different relative orientations. For example, in some non-limiting embodiments, the latching pin116can successfully mate with latching receptacle114at relative rotational orientations of 0°, 90°, 180° and 270°. Furthermore, the latching pin116is centered onto a rear mating surface117of plug connector104so the latching pin is insertable into and latchable by latching receptacle112when plug connector104is rotated to different rotational orientations relative to the adapter base102. AsFIGS. 3A and 3Bshow, this provides a variety of choices for the orientation (and in some case the positions) of power prongs110relative to adapter base102. This feature enables the user to choose an optimal orientation for the power prongs110to prevent the joined adapter base102from physically interfering with adjacent female sockets or other devices, plugs plugged into such adjacent female sockets, etc. This variable orientation feature is for example particularly useful when using the integrated adapter108with an electrical power strip having many closely-spaced sockets connected to other devices.

Electrical Connectivity in Multiple Different Orientations

The recess114of protruding latching receptacle112includes internal electrical conductors that electrically connect with electrical conductors within the latch pins116to electrically connect the plug connector power prongs110to internal electrical components within adapter base102. The latching receptacle112contains a sufficient number of electrical conductors needed to connect with the plug connector(s)104. In some example embodiments, all of plug connectors104have the same number of power prongs110(e.g., two prongs) and latching receptacle112and latching pin116each provide this same number of isolated (non-shorting) electrical connections when they are mated. In other non-limiting configurations, latching receptacle112may have one or more electrical connectors that will be unused when connected to certain plug connectors104but used when connected to certain other plug connectors.

Electromagnetic Latching Mechanism

As will be detailed below, an electromagnetic latching mechanism within adapter base102is used to selectively firmly retain latching pin116within latching receptacle112when power is applied to the integrated adapter108via power prongs110. Thus, in these non-limiting examples, power applied to power prongs110flows through the plug connector104and through the interconnected latching pin116and latching receptacle112into adapter base102. This power applied to the adapter base102causes the adapter base to activate an internal electromagnetic latch that latches the latching pin116into the latching receptacle112. When power ceases flowing through the power prongs110to the latching base102, the latching base unlatches the internal electromagnetic latch to release the latching pin116from the latching receptacle112.

In other embodiments, a spring-biased mechanical latching mechanism is used to latch the latching pin116into the latching receptacle112, and a push button (shown in phantom) is used to release the latching mechanism. While the mechanical latching mechanism (as described above) is simple and cost-effective, advantages can be obtained by using an electromagnetic latching mechanism instead of or in conjunction with the mechanical latching mechanism.

Conceptual Block Diagram of Overall System Including Electromagnetic Latching Mechanism

FIG. 4is a conceptual block diagram of an overall system that uses the integrated adapter108to connect power mains202to one or more appliances204. In this particular non-limiting example, power mains202supplies alternating current (AC) at for example, 100 VAC, 110 VAC, 220 VAC, etc., and appliance204requires a direct current (DC) at a lower voltage such as 5 VDC, 9 VDC, or 12 VDC. The integrated adapter108thus provides an AC-to-DC conversion as well as a voltage stepdown or transformation. However, the principles described herein could be used for supplying AC current from the power mains to an AC appliance or for supplying DC current from the power mains to a DC appliance (no AC-to-DC conversion). Similarly, the principles described herein could be used with or without a voltage stepdown. Nevertheless, a preferred embodiment provides both stepdown and AC-to-DC conversion to allow a lower voltage DC appliance204such as a personal computer, a handheld computing device or other digital appliance to be powered from higher voltage AC power mains202.

In the non-limiting example shown inFIG. 4, plug connector104(shown conceptually rather than structurally) is used as a mains connector to connect to the mains supply202. The plug prongs110are abstractly shown interfacing with mating sockets206of mains supply202. The plug connector104in turn mechanically and electrically connects to adapter base102via the latching pin116which is inserted into and latched by latching receptacle112. In this way, the power supplied by mains supply202is supplied to conductors120within adapter base102.

Adapter base102includes a housing130containing a stepdown transformer and/or circuit122, a rectifier124, a latch control circuit126and an electromagnetic latch128. In the example shown, the stepdown transformer or circuit steps down or transforms the AC voltage from the power mains202to a lower voltage. Such stepdown transformer (inductive or solid state e.g., thyristor-based using silicon controlled rectifiers) circuits are well known in the art. The transformer122in the example shown can operate at a variety of different primary voltages such as 100 VAC, 110 VAC, 220 VAC, etc., and frequencies such as 50 Hz or 60 Hz.

The resulting stepped-down voltage (LV) is rectified and filtered by rectifier/filter124to output filtered DC voltage onto a voltage bus (VBUS)130. The voltage bus130is connected to the appliance204either directly or through another connector(s)132such as USB, barrel connector or any other convenient DC interconnect.

The VBUS130is also provided to power a latch control circuit126. In the example non-limiting embodiment, the latch control circuit126also receives a sense input134from step-down transformer122. The sense input134indicates when power from the power mains202is applied to or removed from adapter base102.

In response to the sense input134, the latch control circuit126selectively applies a latching signal or a delatching signal to electromagnetic latch128via control line136. Specifically, latch control circuit126applies a latching signal to electromagnetic latch128via line136when the sense input134indicates that AC power from the power mains202is applied to the adapter base102, and applies a delatching signal to the magnetic line via line136when the sense input indicates that AC power has been disconnected and is no longer present. The electromagnetic latch128and associated mechanical latching mechanism moves to (or stays in) the latched position/state so long as the latching signal is present, and moves to (or stays in) the delatched position/stage so long as the delatching signal is present. The latched or delatched state of electromagnetic latch128and associated mechanical latching mechanism in turn selectively latch the latching pin116into or release the latching pin from the latching receptacle112.

Example Non-Limiting Latch Control Circuit

In the particular example embodiment of latch control circuit126shown inFIG. 5, a pickup150electromagnetically coupled to the power mains conductor120picks up a low amplitude version of the incoming power mains202AC signal. In the example shown, the pickup150can comprise a short conductor operating as an antenna that is electrically insulated from but runs parallel to a length of the power mains conductor120. Other embodiments could use a small, electrically-isolated but electromagnetically-coupled sympathetic winding of stepdown transformer122or other arrangements as a pickup150.

The low amplitude version of the incoming power mains signal outputted by pickup150is applied to a detector comprising a comparator152and a diode154. The combination of comparator152and diode154operate as a clipper to produce an output pulse each time the AC signal provided by pickup150exceeds a certain positive (or negative) threshold voltage. The resulting frequency detection produces a pulse for each cycle of the incoming AC mains pickup signal. Many other sensing circuits such as polarity or frequency detector could be used since the objective is to determine whether the AC mains signal continues to be present.

The output of diode154comprises a pulse train having a repetition rate equal or proportional to the frequency of AC signal supplied by the power mains202. That is, if the power mains202supplies an AC power signal of 50-60 Hz, the output of diode154will be a 50-60 Hz pulse train (or some multiple thereof) whenever the integrated adapter108is plugged into the power mains202.

The repetitive pulse train is applied to the input of a retriggerable one-shot timer156. The one-shot timer156has two mutually-exclusive output states: “AC present” and “AC absent.” The one-shot timer156begins generating an “AC present” output signal when it begins receiving pulses from diode154, and will continuously generate this “AC present” signal so long as diode154continues to produce pulses indicating that the power mains signal is still being applied to the adapter base102. The time constant of the one-shot timer156is set to greater than 20 milliseconds so it will continue to produce the “AC present” signal so long as the next pulse derived from pickup150arrives within a time window indicative of an at least 50 Hz periodic signal ( 1/50 Hz=0.02 seconds=20 milliseconds).

Upon discontinuance of pulses from the diode154, the one-shot timer156resets, ceases to produce the “AC present” output and instead begins producing the “AC absent” output. The one-shot timer156will continue to produce the “AC absent” output until it again begins receiving pulses from diode154indicating the AC power from power mains202has been restored, at which point it will cease producing “AC absent” and instead begin producing “AC present”.

The “AC present” output of one-shot timer156is connected to control closing of a first switch158, and the “AC absent” output of the one-shot timer is connected to control closing of a second switch160. Because these two one-shot timer156outputs are mutually exclusive, the first and second switches158,160are never closed at the same time. Rather, only one of these two switches158,160is closed at any given time depending on the state of one-shot timer126. A dead time circuit (not shown) ensures that both switches158,160are never closed at the same time, but rather that one has opened completely before the other begins to close and vice versa. [The dead circuit provides sufficient delay in some embodiments so that switch160does not close immediately upon a user suddenly pulling the integrated adapter108out of a power socket, thereby keeping adapter108integrated for a short while as the user pulls out the adapter.]

When the one-shot timer156first begins receiving the repetitive pulse train from diode154indicating that the adapter base102is connected to the power mains, it produces the “AC present” output that closes switch158. Closing switch158connects the VBUS DC power across a series circuit consisting of an electromagnetic latch (solenoid)128connected in series with a capacitor162. Closing switch158causes current to flow through electromagnetic latch128in a first polarity while capacitor162charges. This current flow causes the electromagnetic latch128to generate a magnetic field in a first direction. Once the capacitor162completely charges, only leakage current flows through the electromagnetic latch.

In one example non-limiting embodiment, electromagnetic latch128comprises a solenoid, i.e., a helically wound coil. Inside the coil is a movable permanent magnet armature129. The armature129moves when DC current is applied to the solenoid. The direction in which the armature129moves depends on the polarity of the DC current applied to the solenoid. In the particular example shown, the permanent magnet armature129is pushed in one direction by a solenoid-produced magnetic field of a first direction, and is pushed in the opposite direction by a solenoid-produced magnetic field in a second direction opposite the first direction. When DC current of a first polarity is applied, the armature129moves in a first direction relative to the coil. When DC current of a second polarity opposite to the first polarity is applied, the armature129moves in a second direction relative to the coil opposite the first direction.

When closing of switch158causes DC current flow through electromagnetic latch in a first polarity, the armature129moves in a first direction which pushes a mechanical latching mechanism into a position that latches the latching pin116into latching receptacle112. Once the capacitor162is fully charged, almost no current continues to flow through the series-connected capacitor and the electromagnetic latch128. The only current draw is leakage current, which is very small. Thus, so long as the one-shot timer continues to receive input pulses from diode154indicating the power mains202connection is still present, capacitor162remains charged and the electromagnetic latch128remains in its latched state.

When power from power mains202is removed from adapter base102by for example unplugging the plug connector104from the power mains202, components152,154detect this and control the one-shot156to change state. The “AC present” output of one-shot156becomes inactive and its “AC absent” output becomes active. This state change causes switch158to open and switch160to close. Closing switch160has the effect of discharging the series-connected (charged) capacitor162across the electromagnetic latch128. This discharging of capacitor162across latch128causes current to flow through the latch128in a reverse polarity as compared to the direction of current flow when switch158was closed in response to the “AC present” output of one-shot timer156. The reverse current flow causes the electromagnetic latch128to generate a reverse polarity magnetic field. The capacitance of capacitor162is selected to have sufficient current-storage capacity to not only cause the magnetic field of electromagnetic latch128to collapse, but to also generate a reverse magnetic field of sufficient power and duration to cause the permanent magnet armature129to move from the latched position to the unlatched position. For example, capacitor162may comprise an electrolytic or other suitable large valued capacitor to provide current discharge of sufficient duration to cause the permanent magnet armature129to move to the unlatched position. Moving the armature129to the unlatched position releases latching pin116from latching receptacle112, allowing the user to remove the latching pin from the latching recess114.

In some non-limiting embodiments, additional mechanisms such as rare earth or other magnets M may be used to attract the plug connector104to adapter base102even when the electromagnetic latch128is unlatched, providing a weak (easy to overcome) attraction force that keeps integrated adapter108integrated while still allowing a user to easily pull plug connector104away from adapter base102so the user can replace the plug connector with another plug connector of a different configuration.

Example Non-Limiting Mechanical Structure of Adapter Base102

FIGS. 6, 6A, 6B and 6Cshow exploded views of an example adapter base latching receptacle112and its relationship to electromagnetic latch128. In the example shown, the latching receptacle112is inserted into a beveled window115bwithin a faceplate115cthat in turn is held in position in the adapter base102by a spring-loaded frame115a. A latching mechanism128operates to latch and release a latching pin116that is inserted into the latching receptacle112. The unlatching mechanism128could be a push button operated mechanical device as shown but preferably is an electromagnetic latch as described above (in cases that use the electromagnetic latch, no push button operated release mechanism is required and the mechanical latching device is replaced by an electromagnetic latch).

Example Latching Details

FIG. 7shows a cross-sectional detail of an example non-limiting latching pin116insertable into latching receptacle114. Latching pin116comprises a four-sided shaft (seeFIG. 15) with a distal end portion116a. While this shaft is square in cross-section in the embodiment shown, it could have other shapes such as triangular, pentagonal, hexagonal or cylindrical. A circumferential groove116bdisposed near the distal end portion116aof the latching pin shaft encircles the end of the shaft. In the example shown, the circumferential groove116bis used to engage with latching fingers128a,128b. Because the groove116bis circumferential and the latching pin116is symmetrical, the groove will engage the latching fingers128a,128birrespective of the angular (rotational) orientation of the latching pin116relative to the latching receptacle114. However, in example embodiments, the latching pin116will mate with the latching receptacle114only in discrete relative angular position such as for example 0°, 90°, 180° and 270°. Such discrete angular positions give flexibility while simplifying the design and ensuring stability and good connectivity. Other embodiments with a multisided or cylindrical latching pin shaft could provide angular rotation to any desired relative angular orientation so long as some angular rotation orientations provide no contact (a safety feature). One advantage of the flag-shaped conductor approach is that close tolerances are not required to ensure good connections are established.

In the example embodiment, when the electromagnetic latch128is in the unlatched state, latching fingers128a,128bare retracted away from a latching position and do not engage the latching pin circumferential groove116b. SeeFIG. 7. This retracted position of latching fingers128a,128bpermits the latching pin116to be freely inserted into and removed from latching receptacle114. In some embodiments, the latching fingers128a,128bare spring biased into engagement positions but retract upon insertion of the latching pin116(see angular portions of the latching pin near the distal end) before snapping back into engagement with the latching pin groove116b. The latching fingers128a,128bdisengage from latching pin116through application of force such as by automatic operation of solenoid armature129or, in some embodiments, manual operation of a push button.

However, when the electromagnetic latch128is in the latched state (which occurs only when the latching pin116is fully inserted into the latching receptacle114and conducts power from the power mains202into the adapter base102), latching fingers128a,128bare pushed forward into the circumferential groove116b, thereby engaging the groove and firmly retaining latching pin116within latching receptacle114. SeeFIG. 8.

Electrical Connectivity Between Latching Pin and Latching Receptacle

FIGS. 6 and 7also shows electrical connectors112z1,112z2disposed within the latching receptacle recess114. InFIG. 7, the electrical connector112z1is flag-shaped and made of a conductive material such as copper. In the example shown, the flag portion of the connector covers a portion of one inner side wall of the recess and wraps around the inside corner of the recess and extends to cover a portion of an adjacent side wall of the recess. Similarly, as can be seen inFIG. 6A, a second flag-shaped conductor112z2is disposed on an opposite inner wall of recess114and wraps around the opposite inside corner of the recess to cover a portion of a further adjacent inner wall of the recess. In this way, one conductor112z1covers a portion of two adjacent inner walls of latching receptacle recess114, and another conductor112z2covers a portion of the other two adjacent inner walls of the recess. The flag portions of the conductors112z1,112z2are disposed such that they cannot be contacted by the digits of a human user handling the latching recess114, and are spaced relative to one another so that creepage will not expose the user to a shock hazard.

As can be seen inFIG. 12, the latching pin116supports, on opposite sides, two terminals410,410′ each having angular protruding portions410x,410x′. As the latching pin116is inserted into receptacle recess114, these angular protruding portions410deform to fit within the recess and slide into position onto the conductor flags112z1,112z2. One angular protruding portion410contacts conductor flag112z1, and the other protruding portion410′ contacts conductor flag112z2(or vice versa). Because in one non-limiting embodiment the terminals410,410′ carry alternating current, there is no polarity to worry about and so it does not matter whether angular protruding portion410makes contact with conductor flag112z1or with conductor flag112z2. What is important is that the angular protruding portion410contacts one of flags112z1,112z2and the other angular protruding portion410′ contacts the other one of flags112z1,112z2without any short circuit or other connection between them. This occurs whenever latching pin116is inserted into latching receptacle114irrespective of the relative orientation of the latching pin relative to the receptacle—i.e., at an offset of 0°, 90°, 180° or 270°. Any one of these four discrete angular orientations of latching pin116relative to receptacle recess114will result in excellent connections between the electrical terminals410carried by the latching pin and the connection flags112z1,112z2disposed on the inner walls of the receptacle recess. Thus, good AC electrical connections are made between the latching pin116and the latching receptacle112for any of four different angular orientations of the latching pin relative to the latching receptacle.

Example Plug Connector Structure

FIGS. 9-14show example views of a non-limiting plug connector104(3). TheFIG. 9exploded view details a housing402defining slots404through which a hinged power prong assembly406protrudes. Power prong assembly406is pivotable between an extended position and a retracted position. In the extended position, the power prong assembly406provides extended prongs110that can be inserted into a power socket. In the retracted position, the power prong assembly406is mostly disposed within slots404but protrudes sufficiently (seeFIG. 1) to be manually grasped and pivoted to the extended position.

The plug connector104(3) further includes a clip408and terminals410. The components408,410are disposed within a latching pin assembly412from which latching pin116projects. The clip408provides a “click” feel when prongs406are pivoted to their extended position. The terminals410provide electrical connections between the respective prongs110(3),110(3)′ and electrical conductors within the projecting latching pin116. The terminals410are flexible to smoothly contact with the prongs406. See alsoFIG. 10which shows a detail of how terminal410interfaces with and contacts pivoting prong110(3).FIG. 14shows a further detail of how the terminals410both flexibly contact and are in tension toward prongs110and also descend into latching pin116. Note how the angled out portions410xof terminals410extend from the sides of latching pin116and can be used to establish a high voltage electrical connection with latching receptacle114while still being protected by an insulative housing104xfrom being contacted by the user handling the plug connector104.

FIG. 12further details an internal steel reinforcing pin116mdisposed within the center of latching pin116. The steel reinforcing pin116mor other rigid member is inserted into the tool and co-molded into the latching pin116in order to prevent the latching pin from breaking off or bending under abuse. The steel may also be attracted to the magnetic form of permanent magnet M described above to weakly retain the latching pin116within the latching receptacle112.

As shown inFIG. 12, the distance d from the bottom surface104pto the pin/latch contact point is important to control, as is the distance from the top of the adapter face to the pin/latch contact point, in order to provide a solid latching experience. Additionally, asFIG. 10cross-section shows, the latching pin116and the face116fare fabricated as a single part to shorten the pin/latch tolerance loop. In one embodiment, the outer cover will contact only the plastic face of the adapter along a single edge. The bottom face is the only point of contact on all four sides. The cover will not contact the adapter face on three sides (on the other three sides the face controls contact). Locating on both the face and the cover could result in tilt and create a gap. This is why the pin and face are one integral piece, and the bottom face is used to locate. The face is thus used as the datum for contact (Target=PIN/FACE will be USW to the assembly, and is held flush cover to 0.10 proud of the cover lip. The outer frame cover is not the first point of contact—instead the face is the first contact point.

FIG. 15shows a bottom view of an example plug connector104. IN the example shown, an outer cover452includes an outer cover frame452fmand an outer cover face452fc. The face452fcis, in example embodiments, the datum for contact. Target=pin/face will be USW to the plug connector and is held flush cover to 0.10 proud of the cover lip. The outer cover frame452fmis not used as the first point of contact. This arrangement limits the tolerances that impact the pin<->latch connection.