Power coupling system

FIELD OF THE INVENTION

0001The present invention is related to a pinless power coupling system according to claim 1 and addresses efficient inductive power transmission across substantially flat surfaces.

BACKGROUND

0002Electrical connections are commonly facilitated by the use of plugs and jacks. Power jacks are fixed connectors which are stationary relative to the surface into which they are embedded. Power plugs are movable connectors which are adapted to electrically couple with power jacks. The plug-jack coupling allows a movable device hardwired to the plug to be selectively connected to a power jack and disconnected and removed when required. In such electrical couplings it is common for the plug and jack to be mechanically coupled together and conductively connected using a pin and socket combination. The pin and socket coupling provides a way to align the plug to the jack efficiently and to prevent the two from becoming disconnected while in use and the pin, typically copper or brass, forms a conducting contact with a conductive element lining the socket. Where power is being transmitted, such as in a mains power point, where there is a danger of injury from electrocution, it is common that the pin is provided on the plug so that the live power lines may be safely shielded within the sockets of the power jack. Nevertheless, since the live power lines are not fully insulated there is a risk of injury associated with mains sockets, particularly to children who may be tempted to push small fingers or other objects into a live socket. It is therefore common to provide additional protection such as through the use of socket guards and the like.

0003Moreover, a socket if not maintained, collects dust which may impede electrical connection or even clog the socket, making insertion of the pin difficult. For this reason, power sockets are typically mounted upon walls and are not angled upwards. This configuration also reduces the risk of shorting or electrocution as a result of liquid spillages.

0004Inductive power connectors for providing insulated electrical connection are known. For example,. <patcit id="pcit0001" dnum="US7210940B1"><text>US 7,210,940 B1 to Baily et al.</text></patcit> describes an inductive coupling for transferring electrical energy to or from a transducer and measuring circuit. Baily' s system consists of a male connector having a single layer solenoid wound on a ferromagnetic rod and a female connector having a second single layer solenoid. By inserting the male connector into the female connector, the two solenoids are brought into alignment, enabling inductive energy transfer therebetween. This coupling provides a sealed signal connection without the disadvantages of having exposed contact surfaces.

0005In Baily' s system the female connector still represents a socket and the male connector a pin. Although there are no exposed contact surfaces, such electrical power jacks cannot be located upon surfaces which need to be flat such as table tops, counters and the like. Because such surfaces are often precisely where electrical connection would be most convenient, this results in unsightly and inconvenient, extensive power connecting cables.

0006Other electrical power transmission systems allowing a power receiving electrical device to be placed anywhere upon an extended base unit covering a larger area have been proposed. These provide freedom of movement without requiring the trailing wires inherent in Baily. One such example is described in <patcit id="pcit0002" dnum="US7164255B1"><text>US 7,164,255 B1 to Hui</text></patcit>. In Hui's system a planar inductive battery charging system is designed to enable electronic devices to be recharged. The system includes a planar charging module having a charging surface on which a device to be recharged is placed. Within the charging module, and parallel to the charging surface, is at least one, and preferably an array of primary windings that couple energy inductively to a secondary winding formed in the device to be recharged. Hui's system also provides secondary modules that allow the system to be used with conventional electronic devices not supplied with secondary windings.

0007Such systems are adequate for charging batteries, in that they typically provide a relatively low power inductive coupling. It will be appreciated however, that extended base units such as Hui's charging surface which allows energy transfer approximately uniformly over the whole area of the unit, are not generally suitable for providing the high energy requirements of many electric devices.

0008<patcit id="pcit0003" dnum="US6803744B1"><text>US 6,803,744 B1, to Sabo</text></patcit>, titled "Alignment independent and self-aligning inductive power transfer system" describes an inductive power transfer device for recharging cordless appliances. It also addresses the problem of pinlessly aligning a secondary inductive coil to a primary inductive coil. Sabo's device includes a plurality of inductors arranged in an array and connected to a power supply via switches which are selectively operable to activate the respective inductors.

0009The inductors serve as the primary coil of a transformer. The secondary coil of the transformer is arranged within the appliance. When the appliance is positioned proximate to the power transfer device with the respective coils in alignment, power is inductively transferred from the device to the appliance via the transformer.

0010<patcit id="pcit0004" dnum="US2006202665A1"><text>US 2006/202665 A1</text></patcit> discloses inductively powering a power receiving device placed anywhere over an inductive powering surface having a plurality of primary coils arranged therein that can be energized for transferring power to a portable device placed on the surface. In order for the powering device to detect the presence and location of the secondary coil of the portable device on the inductive powering, the portable device includes a passive locator device.

0011Similarly, <nplcit id="ncit0001" npl-type="b"><text>KOICHI HATANAKA ET AL, "Power Transmission of a Desk with a Cord-Free Power Supply", IEEE TRANSACTIONS ON MAGNETICS, IEEE SERVICE CENTER, NEW YORK, NY, US, (20020901), vol. 38, no. 5, ISSN 0018-9464</text></nplcit>, discloses an inductive powering surface in which multiple primary coils transmit power to a single larger secondary coil but does not disclose any alignment mechanism.

0012Another inductive charger having a detection system is known from <patcit id="pcit0005" dnum="EP0357285A1"><text>EP 0 357 285 A1</text></patcit>.

0013Nevertheless, the need remains for a cost effective and efficient pinless power coupling mechanism and the present invention addresses this need.

SUMMARY OF THE INVENTION

0014Against this background, the invention addresses efficient inductive power transmission across substantially flat surfaces and aims at providing a pinless power coupling system for this purpose.

0015This technical problem is solved by a pinless power coupling system comprising the features of claim 1. Advantageous embodiments are indicated in further claims.

0016The pinless power coupling arrangement comprises at least one pinless power jack comprising a primary coil shieldable behind an insulating layer for inductive coupling to a pinless power plug comprising a secondary coil while the insulating layer is substantially flat and the pinless power plug and the power jack are alignable by an alignment means.

0017Typically, alignment between said power plug and said power jack can be maintained whilst said power plug is rotated through 360 degrees about a central axis.

0018The term "jack" as used herein refers to any fixed connector for receiving and for providing power to an electrical plug. The term "jack" is not defined by the gender of the connector and does not indicate having sockets for receiving protruding pins of a plug.

0019The term "plug" as used herein refers to any moveable connector for electrically connecting to a jack as above. The term "plug" is not defined by the gender of the connector and does not imply having protrusions for fitting into a socket.

0020It will be noted that although gender-based definitions are sometimes used for the terms "jacks" and "plugs", the above definitions are in keeping with IEEE STD 100 and ANSI Y32.16 standards.

BRIEF DESCRIPTION OF THE FIGURES

0021For a better understanding of the invention and to show how it may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings.

0022With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention; the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. In the accompanying drawings: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> is a block diagram schematically representing the main features of an inductive power transfer system, usable with the present invention;</li><li><figref idref="f0001">Fig. 2a</figref> is a schematic representation of a pinless power coupling consisting of a pinless power jack and a pinless power plug, usable with the present invention;</li><li><figref idref="f0002">Fig. 2b-d</figref> show three exemplary applications of the power coupling of <figref idref="f0001">Fig. 2a</figref> providing power to a computer, light bulb and pinless power adaptor;</li><li><figref idref="f0003">Figs. 3a and 3b</figref> show an exemplary configuration for an induction coil in schematic and exploded representation respectively;</li><li><figref idref="f0004">Figs. 4a-c</figref> show three exemplary tactile alignment mechanisms for aligning a pinless power plug to a pinless power jack, wherein <figref idref="f0004">Fig. 4c</figref> shows an embodiment of the invention;</li><li><figref idref="f0005">Figs. 5a-h</figref> show eight magnetic configurations for use in a tactile alignment mechanism for a pinless power coupling;</li><li><figref idref="f0006">Figs. 6a-e</figref> show three exemplary plug-mounted visual alignment mechanisms for a pinless power coupling;</li><li><figref idref="f0007">Figs. 7a-d</figref> show four exemplary surface-mounted visual alignment mechanisms for a pinless power coupling;</li><li><figref idref="f0008">Figs. 8a and 8b</figref> show audible alignment means for use with the pinless power coupling;</li><li><figref idref="f0009">Fig. 9</figref> shows an exemplary optical transmitter for regulating power transfer to a computer via a pinless power coupling;</li><li><figref idref="f0010">Fig 10</figref> is a block diagram illustrating the main features of an exemplary signal transfer system for initiating and regulating inductive power transfer from the pinless power plug;</li><li><figref idref="f0011">Fig. 11a</figref> shows a power surface including an array of pinless power jacks in accordance with yet another embodiment of the invention;</li><li><figref idref="f0011">Fig. 11b</figref> shows two movable pinless power plugs lying upon the power surface of <figref idref="f0011">Fig. 11a</figref>;</li><li><figref idref="f0012">Fig. 11c</figref> shows a power plug provided with two secondary coils for coupling with primary coils of the power surface of <figref idref="f0011">Fig. 11a</figref>;</li><li><figref idref="f0012 f0013 f0014">Figs. 12a-c</figref> show three exemplary applications of the power surface of <figref idref="f0011">Fig. 11a</figref> providing power to a computer, light bulbs and pinless power adaptors respectively, and</li><li><figref idref="f0015">Fig. 13</figref> is a flow diagram flowchart showing a method for transferring an optical regulation signal between a primary unit and a secondary unit via an intermediate layer.</li></ul>

DESCRIPTION OF THE PREFERRED EMBODIMENTS

0023Reference is now made to <figref idref="f0001">Fig. 1</figref> which is a 1000 for pinlessly providing power to an electric load 140, usable with the invention. The power transfer system 1000 includes a pinless power coupling 100, an alignment mechanism 200 and a power regulator 300.

0024The pinless power coupling 100 comprises a pinless power jack 110 and a pinless power plug 120. The pinless power jack 110 includes a primary inductive coil 112 wired to a power supply 102 via a driving unit 104. The pinless power plug 120 includes a secondary inductive coil 122 which is wired to the electric load 140. When the secondary coil 122 is brought close to the primary coil 112 and a variable voltage is applied to the primary coil 112 by the driving unit 104, power may be transferred between the coils by electromagnetic induction.

0025The alignment mechanism 200 is provided to facilitate aligning the primary coil 112 with the secondary coil 122 which improves the efficiency of the inductive coupling. The regulator 300 provides a communication channel between the pinless power plug 120 and the pinless power jack 110 which may be used to regulate the power transfer.

0026The various elements of the pinless power transfer system 1000 may vary significantly between embodiments of the present invention. A selection of exemplary embodiments are described herebelow. These are not to be understood as limiting the scope of the invention in any way.

Pinless Power Coupling

0027Reference is now made to <figref idref="f0001">Fig. 2a</figref> which shows a pinless power coupling 100, usable with the invention. A pinless power jack 110, which may be incorporated into a substantially flat surface 130 for example, is couplable with a pinless power plug 120. The pinless power jack 110 includes an annular primary coil 112 shielded behind an insulating layer, which may be hardwired to a power source 102 via a driving unit 104. Driving electronics may include a switching unit providing a high frequency oscillating voltage supply, for example.

0028The pinless power plug 120 includes an annular secondary coil 122 that is configured to inductively couple with the primary coil 112 of the pinless power jack 110 to form a power transferring couple that is essentially a transformer. Optionally, a primary ferromagnetic core 114 is provided in the pinless power jack 110 and a secondary ferromagnetic core 124 is provided in the pinless power plug 120 to improve energy transfer efficiency.

0029It will be appreciated that known pinned power couplings of the prior art cannot be readily incorporated into flat surfaces. The nature of any pinned coupling is that it requires a socket into which a pin may be inserted so as to ensure power coupling. In contradistinction, the pinless power coupling 100 has no pin or socket and may, therefore, be incorporated behind the outer face of a flat surface 130, such as a wall, floor, ceiling, desktop, workbench, kitchen work surface, shelf, door or the like, at a location where it may be convenient to provide power.

0030It is specifically noted that because the primary coil 112 is annular in configuration, alignment of the primary coil 112 to the secondary coil 122 is independent of the angular orientation of the pinless power plug 120. This allows the pinless power plug 120 to be coupled to the pinless power jack 110 at any convenient angle to suit the needs of the user and indeed to be rotated whilst in use.

0031For example, a visual display unit (VDU) may draw its power via a pinless power plug 120 aligned to a pinless power jack 110 incorporated into a work desk. Because of the annular configuration of the coils 112, 122, the angle of the VDU may be adjusted without the pinless coupling 100 being broken.

0032Prior art inductive coupling systems are not easily rotatable. For example, in order to achieve partial rotation, the system described in United States Patent No. <patcit id="pcit0006" dnum="US6803744B"><text>6,803,744, to Sabo</text></patcit>, requires the coils to be connected by flexible wires or brushes to concentric commutators on the body of a non-conductive annular container. Even so, Sabo's system allows rotation of only about half the intercoil angle. In contradistinction, the pinless power plug 120 may be rotated through 360 degrees or more, about the central axis of the annular primary coil 110 whilst continually maintaining the power coupling 100.

0033It is known that inductive energy transfer is improved considerably by the introduction of a ferromagnetic core 114, 124. By optimization of the coupling 100, appropriate electrical loads, such as standard lamps, computers, kitchen appliances and the like may draw power in the range of 10W - 200W for example.

0034Three exemplary applications of the pinless power jack 110 of <figref idref="f0001">Fig. 2a</figref>, are illustrated in <figref idref="f0002">Figs. 2b-d</figref>. With reference to <figref idref="f0002">Fig. 2b</figref>, a computer 140a is shown connected by a power cord 121a to a first pinless power plug 120a. The pinless power plug 120a is inductively coupled to a pinless power jack 110 embedded in a desk top 130. The pinless power plug 120a may thereby draw power from the pinless power jack 110 to power the computer 140a, to charge its onboard power cells or both. The parameters such as charging voltage and current for power provision to computers depends upon the model of the computer and therefore the pinless power plug 120a may be adapted to provide a range of voltages, typically between 5-20V and may transfer power at up to 200W. Alternatively or additionally, a variety of pinless power jacks and/or pinless power plugs may be provided which transfer various power levels for various appliances.

0035With reference to <figref idref="f0002">Fig. 2c</figref>, a light bulb 140b connected to a light socket 121b integral to a second pinless power plug 120b is shown. The pinless power plug 120b may be inductively coupled to a pinless power jack 110 by being aligned therewith, and supplies power directly to the light bulb 140b. It is noted that the voltage and power to be provided by the power plug 120b depends upon the rating of the specific light bulb 140b. The power jack 110 may be configured to provide an appropriate power level and voltage such as 1-12V for flash-light type bulbs or 110V for mains bulbs in North America or 220V for mains bulbs in Europe. Alternatively the secondary coil in the plug 120b may both transmit and step down the voltage.

0036Referring now to <figref idref="f0002">Fig. 2d</figref>, a pinless power plug adaptor 120c is shown having a conventional power socket 140c thereupon, into which an electrical load (not shown) may be plugged using a conventional power cable (not shown) with a conventional pinned plug thereupon. The pinless plug adaptor 120c is shown coupled to a power jack 110 embedded into a flat surface 130. It is noted that a pinless power plug adaptor 120c may be coupled with a pinless jack 110 thereby allowing electrical power to be supplied to conventional electrical devices having pinned plugs. The pinless power plug adaptor 120c is typically configured to provide a mains voltage signal of 110V AC in North America or 220V AC in Europe although other voltages, including DC voltages via an internal rectifier may be provided where required.

0037The induction coils 112, 122 for use in the pin-less power coupling 100 may be made of coiled wires or they may be manufactured by a variety of techniques such as screen printing, or etching for example.

0038<figref idref="f0003">Figs. 3a and 3b</figref> schematically represent an exemplary induction coil 1200, usable with the invention in schematic and exploded views respectively. The induction coil 1200 is annular in form and is suitable for use as a primary coil 112 in a pinless power jack 110 or for use as a secondary coil 122 in a pinless power plug 120. The coil is noted to provide a particularly good coupling for its overall size. An induction coil 1200 is formed by stacking a plurality of conducting rings 1202a-e upon a base board 1214. The induction coil 1200 is in contact with two point contacts 1212a, 1212b upon the base board 1214. Each conducting ring 1202 has a leading protruding contact 1208 and a trailing protruding contact 1206 which protrude radially from the center of a split ring 1204 and are located on either side of insulating gap 1210.

0039The conducting rings 1202a-e are stacked in such a manner that each ring is insulated from the rings adjacent to it. The insulating gaps 1210 in the conducting rings 1202 are configured such that the leading protruding contact 1208a of a first ring 1202a makes contact with the trailing protruding contact 1206b of a second ring 1202b. In turn the leading protruding contact 1208b of the second ring 1202b makes contact with the trailing protruding contact 1206c of a third ring 1402c and so forth until all the rings 1202a-e stack together to form an induction coil 1200. The leading protruding contact of the final ring 1208e and the trailing protruding contact of the first ring 1206a are extended to form electrical contact with contact points 1212a, 1212b upon the base board 1214. It will be appreciated that this configuration produces an annular induction coil 1200 with a free central axis 1203 which may accommodate inter alia a ferrite core, a magnetic alignment mechanism (see below) and/or an optical signal transfer system (see below).

0040The individual rings 1202a-e may be manufactured by a variety of techniques such as by circuit sandwiching, circuit printing, fabrication printing, circuit etching, stamping and the like. Although the induction coil 1200 shown in <figref idref="f0003">Figs. 3a and 3b</figref> consists of a mere five rings 1202a-e, it will be appreciated that the number of rings that may be stacked to form induction coils in this manner may vary considerably, as may their dimensions. Thus induction coils with the desired properties may be formed.

Alignment Mechanisms

0041The efficiency of the power coupling 100, depends upon the alignment between the secondary coil 122 of the pinless power plug 120 and the primary coil 112 of the pinless power jack 110. Where the substantially flat surface 130 is fabricated from transparent material such as glass or an amorphous plastic, such as PMMA for example, the user is able to see the pinless power plug 110 directly and may thus align the pinless plug 120 to the pinless jack 110 by direct visual observation. However, where the substantially flat surface 130 is opaque alternative alignment mechanisms 200 may be necessary. Such alignment mechanisms 200 may include tactile, visual and/or audible indications, for example.

0042With reference now to <figref idref="f0004">Figs. 4a-c</figref>, three exemplary tactile alignment mechanisms 210, 220, 230 are shown, wherein <figref idref="f0004">Fig. 4c</figref> shows an embodiment of the invention. Referring particularly to <figref idref="f0004">Fig. 4a</figref>, a first tactile alignment mechanism 210 is shown wherein the pinless power jack 110 includes a central magnetic snag 212 surrounded by an annular primary coil 112 and the corresponding pinless power plug 120 includes a central magnetic anchor 214 surrounded by an annular secondary coil 122.

0043The primary coil 112 consists of a primary conducting wire 113, preferably a litz wire which is wound around a primary ferromagnetic core 114 and the secondary coil 122 consists of a secondary conducting wire 123, again preferably a litz wire which is wound around a secondary ferromagnetic core 124. When aligned, the primary ferromagnetic core 114 and the secondary ferromagnetic core 124 form a magnetic couple that increases the magnetic flux linkage between the primary coil 112 and the secondary coil 122, allowing electrical energy to be transmitted more efficiently therebetween.

Tactile Alignment Mechanisms

0044The central magnetic snag 212 is configured to engage with the magnetic anchor 214 carried by the pinless power plug 120, when the secondary coil 122 is optimally aligned to the primary coil 112 of the pinless power jack 110. It will be appreciated that the attraction between the magnetic anchor 214 and the magnetic snag 212 may be felt by an operator, thereby providing a tactile indication of alignment. In addition, the anchor-snag arrangement, once engaged, also serves to lock the pinless power plug 120 into alignment with the pinless power jack 110. The combination of a central circular magnetic snag 212 and a concentric annular primary coil 112, allows the plug 120, having a central magnetic anchor 214, to rotate around a central axis without losing alignment and thus to be aligned at any orientation.

0045A second tactile alignment mechanism 220 is shown in <figref idref="f0004">Fig. 4b</figref> wherein pinless power jack 110 includes four magnetic corner snags 222a-d which are arranged at four points around primary coil 112, being a primary conducting wire 113 wound around a primary ferromagnetic core 114. The four magnetic corner snags 222a-d are configured to magnetically couple with four magnetic corner anchors 224a-d carried by a pinless power plug 120, when the primary coil 112 and secondary coil 122 are aligned.

0046Where rotation of the secondary coil 122 may impede energy transfer or is otherwise undesirable, multiple magnetic snags 222 may be used to limit the rotation of the plug 120 about its central axis to four specific alignment angles. At each of the compass points, the secondary ferromagnetic core 124 is orientated and aligned to the primary ferromagnetic core 114. The primary ferromagnetic core 114 and the secondary ferromagnetic core 124 thus provided, form a magnetic couple that increases the magnetic flux linkage between the primary coil 112 and the secondary coil 122, allowing electrical energy to be transmitted more efficiently therebetween. It will be appreciated that the number and configuration of multiple magnetic snags 222 and magnetic anchors 224 may be selected to provide various multiple discrete alignment angles.

0047With reference to <figref idref="f0004">Fig. 4c</figref> showing an embodiment of the invention, a third tactile alignment mechanism 230 is shown, wherein the pinless power jack 110 includes an annular magnetic snag 232 concentric with a primary coil 112. The annular magnetic snag 232 is configured to engage with an annular magnetic anchor 234 concentric with a secondary coil 122 in a pinless plug 120. The annular configuration provides a free central axis which is used to accommodate an optical transmitter 310 and an optical receiver 320 of an optical signal system for the regulation of power transfer. The third tactile alignment mechanism 230 allows the plug 120 to rotate around its central axis without compromising the alignment between the primary coil 112 and the secondary coil 122, or between the optical transmitter 310 and the optical receiver 320 of the optical signal system. The power plug 120 may thus to be orientated at any angle to suit requirements.

0048For magnetic coupling, it will be appreciated that a permanent or electro magnet in the jack may exert an attractive force on a second permanent or electromagnet in the plug. Alternatively, the plug may be fitted with a piece of ferrous material that is attracted to a magnet but is not itself, magnetic. Furthermore, the jack may include a piece of iron that is attracted to a magnet, and the plug may be provided with a permanent or with an electromagnet. By way of illustration of this, with reference to <figref idref="f0005">Figs. 5a-h</figref>, eight alternative magnetic alignment mechanisms for use in coupling a pinless power plug 120 with a pinless power jack 110 are shown. A permanent magnetic snag 241 may couple with any of a permanent magnetic anchor 244, an electromagnetic anchor 245 or a ferromagnetic element 246. An electromagnetic snag 242 may couple with any of a permanent magnetic anchor 244, an electromagnetic anchor 245 or a ferromagnetic element 246. A ferromagnetic snag 243 may couple with a permanent magnetic anchor 244, or an electromagnetic anchor 245.

0049It is noted that a primary ferromagnetic core 114 of a pinless power jack 110 may itself serve as a ferromagnetic snag 243. Alternatively, the primary coil 112 may serve as an electromagnetic snag 242. It is further noted that a secondary ferromagnetic core 124 of a pinless power plug 120 may serve as a ferromagnetic anchor 246. Alternatively, the secondary coil 122 may serve as an electromagnetic anchor 245.

0050A preferred magnetic alignment configuration is shown in <figref idref="f0005">Fig. 5a</figref> illustrating a permanent magnetic snag 241 configured to couple with a permanent magnetic anchor 244. The orientations of the magnetic snag 241 and the magnetic anchor 244 are such that facing ends have opposite polarity so that they are mutually attractive. It is noted that in certain embodiments two distinct types of pinless power jacks 120 are provided for coupling with two distinct types of pinless power plugs, for example, a high power coupling and a low power coupling. In such embodiments it is important to avoid a low power plug being aligned with a high power jack, for example. The magnetic anchors may prevent incorrect coupling by using opposite polarities for each type of coupling. Thus, the low power plug may have North seeking polar magnetic anchor, say, to engage with a South seeking polar magnetic snag on the low power jack and the high power plug may have a South seeking polar magnetic anchor to engage with a North seeking polar magnetic snag on the high power jack. If the low power plug of this embodiment is placed proximate to the high power jack the North seeking polar anchor repels the North seeking polar snag and the couple can not be aligned.

0051It will be appreciated that, apart from magnetic mechanisms, other anchor-and-snag type tactile alignment means may alternatively be used such as suckers, hook-and-loop arrangements, ridge-and-groove arrangements and the like. Likewise these may be designed to selectively couple with only a selection of different power jacks in a common surface.

Visual Alignment Mechanisms

0052With reference to <figref idref="f0006">Figs. 6a-e</figref> exemplary visual alignment mechanisms for a pinless power plug 120 are shown. <figref idref="f0006">Figs. 6a-c</figref> show a pinless power plug 120 having a first visual indicator 250 consisting of two indicator LEDs: a rough alignment indicating orange LED 252 and fine alignment indicating green LED 254. A pinless power jack 110 is concealed beneath an opaque surface 130. <figref idref="f0006">Fig. 6a</figref> shows the pinless power plug 120 at a large distance from the pinless power jack 110 with neither of the two indicator LEDS being activated. <figref idref="f0006">Fig. 6b</figref> shows the pinless power plug 120 partially aligned with the pinless power jack 110 and the orange indicator LED 252 being lit up. This alerts a user that the plug 120 is in proximity with a pinless power jack 110, but is not properly aligned therewith. Referring to <figref idref="f0006">Fig. 6c</figref>, when the pinless power plug 120 is optimally aligned with the pinless power jack 110, the green indicator LED 254 is activated to signal to a user that the plug 120 and (concealed) jack 110 are properly aligned and optimal power transfer is possible.

0053<figref idref="f0006">Fig. 6d</figref> shows a second visual indicator consisting of a plurality of LEDs in a strip 260; it being appreciated that a larger number of LEDs provides for a greater degree of graduation in indication of proximity, and helps the user home in on the concealed jack. With reference to <figref idref="f0006">Fig. 6e</figref>, showing a third visual indicator, instead of or in addition to LEDs, an LCD display 265 may provide an alternative visual indicator, which can, in addition to providing indication of the degree of alignment, also provide indication of the current drawn by the load coupled to the plug, for example.

0054By their nature, LEDs are either illuminated or not illuminated, however proximity data may be encoded by flashing, frequency or the like. The intensity of power supplied to other types of indicator lamps may be used to indicate the degree of coupling, or a flashing indicator lamp may be provided, such that the frequency of flashing is indicative of degree of alignment. Indeed, where the load is an incandescent light source or the like, it may be used directly for alignment purposes, since poor alignment results in a noticeable dimming affect.

0055Additionally or alternatively to plug-mounted visual indicators for jack-plug alignment surface-mounted visual indicators may be provided. Thus, with reference to <figref idref="f0007">Figs. 7a-d</figref>, various exemplary visual alignment mechanisms are shown located upon a flat surface 130 in which a pinless power jack 110 has been embedded. In <figref idref="f0007">Fig. 7a</figref>, showing a fourth visual indicator, a mark 270 has been made on the flat surface 130 directly above the concealed pinless power jack 110. This enables the user to physically align the plug with the mark 270 and thus with the concealed jack <figref idref="f0007">Fig. 7b</figref> shows a fifth visual indicator 272 consisting of two indicator LEDs embedded in the surface 130. This works as per the comparative examples of <figref idref="f0006">Figs. 6b and 6c</figref>, mutatis mutandis, to provide a graduated indication of alignment. Similarly, <figref idref="f0007">Fig. 7c</figref> shows a sixth visual indicator 274 consisting of a plurality of LEDs in a strip embedded in the surface 130 for a more graduated degree of alignment indication and <figref idref="f0007">Fig. 7d</figref> shows a seventh visual indicator 276 consisting of an LCD display embedded in the surface 130.

Audible Alignment Mechanisms

0056Non-visual alignment means may alternatively or additionally be provided for example, an audible signal may assist the visually impaired attain alignment. As shown in <figref idref="f0008">Fig. 8a</figref>, a pinless power plug 120 may include a buzzer 280. The buzzer 280 may be configured to provide graduated indication of proximity to alignment for example by variation in tone, pitch, volume, timbre, beep frequency or the like. Alternatively an audible alignment means may be surface-mounted as shown in <figref idref="f0008">Fig. 8b</figref>, showing a buzzer 285 embedded in the surface 130, configured to buzz in a manner indicating whether there is, and extent of alignment.

Power Regulation

0057Efficient power transfer requires regulation. In order to regulate the characteristics of the power provided to the secondary coil 122, such as voltage, current, temperature and the like, feedback from the device to the power jack 110 is desirable. According to further embodiments of the present invention, a power regulator 300 provides a communications channel between the power plug 120 wired to the load and the power jack 110.

0058A first exemplary power regulator 300 is illustrated in <figref idref="f0009">Fig. 9</figref>. An optical transmitter 310, such as a light emitting diode (LED), is incorporated within the pinless power plug 120 and operably configured to transmit electromagnetic radiation of a type and intensity capable of penetrating both the casing 127 of the pinless power plug 120, and a shielding layer 132 of the substantially flat surface 130. An optical receiver 320, such as a photodiode, a phototransistor, a light dependent resistors or the like, is incorporated within the pinless power jack 110 for receiving the electromagnetic radiation transmitted through the surface layer 132. In preferred embodiments the optical transmitter 310 and the optical receiver 320 are configured along the axis of the annular primary coil 112. This permits alignment to be maintained through 360 degree rotation of the pinless power plug 120.

0059It is noted that many materials are partially translucent to infra-red light. It has been found that relatively low intensity infra red signals from LEDs and the like, penetrate several hundred microns of common materials such as plastic, cardboard, Formica or paper sheet, to a sufficient degree that an optical receiver 320, such as a photodiode, a phototransistor, a light dependent resistor or the like, behind a sheet of from 0.1 mm to 2 mm of such materials, can receive and process the signal. For example a signal from an Avago HSDL-4420 LED transmitting at 850nm over 24 degrees, may be detected by an Everlight PD15-22C-TR8 NPN photodiode, from behind a 0.8 mm Formica sheet. For signaling purposes, a high degree of attenuation may be tolerated, and penetration of only a small fraction, say 0.1% of the transmitted signal intensity may be sufficient. Thus an infra-red signal may be used to provide a communication channel between primary and secondary units galvanically isolated from each other by a few hundred microns of common sheet materials such as wood, plastic, Formica, wood veneer, glass etc.

0060Where the intermediate surface layer is opaque to infra-red, particularly where the intermediate surface layer is relatively thick, an optical path may be provided to guide the signal to the optical receiver 320. Typically, the optical path is a waveguide such as an optical fiber, alternatively, the optical receiver 320 may be placed behind an opening in the face of the surface and covered with a translucent window.

0061In inductive couples, the communication channel may be used to transfer data between the primary and the secondary coils. The data transferred may be used to regulate the power transfer, for example. Typically the signal carries encoded data pertaining to one or more items of the list below: <ul id="ul0002" list-style="none"><li>▪ the presence of the electric load;</li><li>▪ the required operating voltage for the electric load;</li><li>▪ the required operating current for the electric load;</li><li>▪ the required operating temperature for the electric load;</li><li>▪ the measured operating voltage for the electric load;</li><li>▪ the measured operating current for the electric load;</li><li>▪ the measured operating temperature for the electric load, or</li><li>▪ a user identification code.</li></ul>

0062Such a signal may be useful in various inductive energy couples usable with the present invention such as transformers, DC-to-DC converters, AC-to-DC converters, AC-to-AC converters, flyback transformers, flyback converters, full-bridge converters, half-bridge converters and forward converters.

0063Referring now to <figref idref="f0010">Fig. 10</figref>, a block diagram is presented illustrating the main features of an exemplary signal transfer system for initiating and regulating inductive power transfer according a second embodiment of the power regulator 300. An inductive power outlet, such as a pinless power jack 110, is configured to couple with a secondary unit, such as a pinless power plug 120, separated therefrom by a surface layer 130. Power is transferred to an electric load 140 wired to the pinless power plug 120.

0064The pinless power jack 110 includes a primary inductive coil 112, a half-bridge driver 103, a multiplexer 341, a primary microcontroller 343, a tone detector 345 and an optical receiver 347. The secondary unit, such as pinless power plug 120, consists of a secondary coil 122, a receiver 342, a secondary microcontroller 344, an optical transmitter 346 and a load connecting switch 348.

0065The primary inductive coil 112 of the inductive power outlet is driven by the half-bridge driver 103 which receives a driving signal S_D from the multiplexer 341. The multiplexer 341 selects between an initialization signal S_I or a modulation signal S_M. The initialization signal S_I provides a detection means for activating the inductive power outlet 110 when a secondary unit 120 is present. Once active, the modulation signal S_M provides a means for regulating power transfer from the power outlet 110 to the secondary unit 120.

0066Secondary unit detection is provided by the primary microcontroller 343 intermittently sending an initialization signal S_I to the multiplexer 341 when the power outlet 110 is inactive. The multiplexer 341 relays the initialization signal S_I to the half-bridge driver 103, which results in a low powered detection pulse being transmitted by the primary coil 112. If a secondary unit 120 is aligned with the inductive power outlet 110, the low powered detection pulse is inductively transferred to the secondary coil 122 across the surface layer 130. The receiver 342 is configured to receive this detection pulse and relay a detection signal to the secondary microcontroller 344 which sends a signal to the load connector switch 348 to connect the load and triggers the optical transmitter 346 to transmit an optical signal through the surface layer 130 confirming that the secondary unit 120 is in place. The optical signal is received by the optical receiver 347 in the power outlet 110, and is then relayed to the tone detector 345 which sends a confirmation signal to the primary microcontroller 343. The primary microcontroller 343 then activates the power outlet 110 by triggering the multiplexer 341 to select the modulation signal S_M to regulate the power transfer.

0067The modulation signal S_M comes directly from the optical receiver 347 and is used to regulate the duty cycle of the half-bridge driver 103. Power transferred to the secondary unit 120 is monitored by the secondary microcontroller 344. The secondary microcontroller 344 generates a modulation signal S_M and sends it to the optical transmitter 346, which transmits a digital optical signal. The modulation signal S_M is thus received by the optical detector 347 of the primary unit 110, relayed to the multiplexer 341 and used to regulate the half-bridge driver 103.

0068Prior art inductive power transfer systems control and regulate power from the primary unit 110. In contradistinction, it is a feature of this second embodiment of the power regulator that the power transfer is initiated and regulated by a digital signal sent from the secondary unit 120. One advantage of this embodiment of the invention is that the regulation signal is determined by the secondary microcontroller 344 within the pinless power plug 120, which is hard wired to the load. Therefore conductive communication channels to the secondary microcontroller 344 may be used to transmit analogue signals to the secondary microcontroller 344 for monitoring the power transfer and a digital signal may be used for communicating between the pinless power plug 120 and the pinless power jack 110.

Multicoil Systems

0069Alignment of a pinless power plug to a pinless power jack may be facilitated by using a plurality of induction coil and thereby increasing the number of alignment locations.

0070A plurality of pinless power jacks 110a-n are shown in <figref idref="f0011">Fig. 11a</figref> arranged into a power array 1100 usable with the invention covering an extended surface 1300. The power array 1100 allows for a pinless power plug 120 to be aligned with a power jack 110 in a plurality of locations over the surface 1300. It is noted that although a rectangular arrangement is represented in <figref idref="f0011">Fig. 11a</figref>, other configurations such as a hexagonal close packed arrangement, for example, may be preferred. Optionally multiple layers of overlapping power jacks 110 may be provided. Since a power plug may be placed in alignment with any of the power jacks 110a-n, a power supplying surface may be provided which can provide power to a plug 120 placed at almost any location thereupon, or even to a plug in motion over the power array 1100.

0071With reference to <figref idref="f0011">Fig. 11b</figref>, two pinless power plugs 120A, 120B are shown lying upon a single power array 1100 including a plurality of embedded jacks. The plugs 120A, 120B are free to move parallel to the surface 1300 as indicated by the arrows. As a plug 120, moving along the power array 1100, approaches a jack 110, an anchor 214 associated with the 120 couples with a snag 212 associated with a jack 110 so bringing the primary coil 112 into alignment with a secondary coil 122.

0072When a power plug 120A lies between two jacks 110k, 110l, its anchor 214a is not engaged by any snag 212. Consequently, the secondary coil 122A of the power plug 120A is not aligned with any primary coil 112. In such a situation an orange LED indicator 252A for example, may be used to indicate to the user that the plug 120A is close to but not optimally aligned with a primary coil 112. Where a power plug 120B lies directly in line with power jack 110b such that its anchor 214B is engaged by a snag 212b embedded in the power jack 110b, the secondary coil 122B is optimally aligned to the primary coil 112b of the jack 110b and this may be indicated for example by a green LED indicator 254B.

0073Reference is now made to <figref idref="f0012">Fig. 11c</figref> showing a power plug 1200 provided with multiple secondary coils 1202a, 1202b usable with the invention. Efficient inductive power transfer may occur when either one of the power plug's secondary coils 1202 is aligned to any primary coil 112. It is noted that known multicoiled power plugs such as the double coiled plug described in United States Patent No. <patcit id="pcit0007" dnum="US6803744B"><text>6,803,744, to Sabo</text></patcit>, need to be specifically and non-rotatably aligned such that the two secondary coils are both coupled to primary coils simultaneously. In contradistinction to the prior art, in the multicoiled power plug 1200, only one secondary coil 1202 aligns with one primary coil 110 at a time. Alignment may thereby be achieved at any angle and the multicoiled power plug 1200 may be rotated through 360 degrees or more about the axis X of the primary coil 110.

0074Furthermore, in the multicoiled power plug 1200, the distance between the secondary coils 1202 may advantageously be selected to differ from the inter-coil spacing of the power platform array 1100. The multicoil power plug 1200 may then be moved laterally over the power surface 1100 and the driving unit of the power array 1100 may activate the primary coils located closest to the multicoil power plug 1200. As the multicoil power plug 1200 is moved laterally, the secondary coils 1202a, 1202b both receive power from the primary coils in their vicinity. The power transferred to both the secondary coils 1202a, 1202b undergoes diode summation to produce a total voltage output. Because the two secondary coils 1202a, 1202b are never both aligned simultaneously, the total output voltage is smoothed and power fluctuations normally associated with power transfer to moving power plugs may be prevented. This increases overall efficiency and reduces the need for large variations in the power provided to the power array 1100.

0075Inductive power transfer models have been simulated to measure the efficiency of power transfer to multiple secondary coils from a power surface with inter coil separation of 8.8 cm. With voltage applied only to the primary coil closest to a pair of secondary coils separated by 4.4 cm (half the surface intercoil separation), the efficiency of total energy transferred to the pair of secondary coils does not fall below 80% as the pair of secondary coils undergoes lateral translation along the surface. This efficiency is further improved by increasing the number of secondary coils, for example in simulations of a triplet of secondary coils spaced at 2.9 cm from each other, efficiencies of 90% were achieved.

0076In other embodiments of the invention where a multilayered power surface is provided, each layer of primary coil arrays is offset from the others, for example by half the surface intercoil separation. A single coiled pinless power plug may be placed upon the multilayered power surface and the driving unit of the power surface configured to activate only the primary coils within the multilayered power surface located closest to alignment with the secondary coil of the power plug regardless of its layer. In this way, the voltage, efficiency and power transferred to the receiving coil are greatly stabilized.

0077Power arrays 1100 may be incorporated within any flat surface 1300 where it is convenient to provide power. Such surfaces include walls, floor areas, ceilings, desktops, workbenches, kitchen work surfaces and counter tops, shelves, doors and door panels and the like.

0078For example, <figref idref="f0012">Fig. 12a</figref> shows an exemplary horizontal power array 1100 and a pinless power plug 120a electrically coupled to a computer 140a by means of a connecting cable 121a. The pinless power plug 120a is placed upon the power array 1100 and is inductively coupled to a pinless power jack 110 therewithin. Power supplied to the computer 140a may power the computer 140a directly and/or recharge a rechargeable power cell thereof. The arrangement of <figref idref="f0012">Fig. 12a</figref> with pinless power plugs 120a connected by cables 121a, typically reduces the length and number of wires and cables 121a necessary when connecting a computer 140a to a power source, and thus may be beneficial in conference rooms and the like, where such wires are obstructing, unsightly and generally inconvenient. It is noted that the pinless power plug 120a may alternatively be integral to the computer 140a, and the connecting cable 121a thereby dispensed with altogether.

0079<figref idref="f0013">Fig. 12b</figref> shows an exemplary power array 1100 that is inverted and horizontal for fixing to a ceiling, for example. Two pinless lighting plugs 120b carrying light sockets 121b for accommodating light bulbs 140b are shown. The lighting plugs 120b are movable and may be coupled to any one of the plurality of pinless power jacks 110 of the power array 1100. Strong magnetic anchors 214 carried by the lighting plugs 120a exert a force upon the magnetic snags 212 embedded in the power array 1100 of sufficient strength to support the weight of the lighting plugs 120a, usable with the invention. In this way, pinless lighting plugs 120a may be easily moved and reattached at different locations around the power array 1100.

0080It will be noted that the power array 1100 shown in <figref idref="f0013">Fig. 12b</figref> is inverted, allowing lighting plugs 120b to be suspended therebeneath. For many lighting applications, such as for the lighting of a room, such an arrangement is preferred as overhead lighting is less likely to be obscured by objects than lower level lighting. However a lighting power surface may be hung vertically or embedded into a wall, or indeed placed underfoot or in any other orientation.

0081It is noted that domestic incandescent light bulbs generally require power in the range of 10-150 watts, it is thus desirable for a lighting plug 120b to supply electricity at this power. The inductive transmission of energy in this power range is enabled by the efficient alignment of highly efficient coils such as that shown in the configuration of <figref idref="f0003">Figs. 3a and 3b</figref> described herein. Low power lighting solutions, such as fluorescent bulbs, LEDs and the like, typically use lower power plugs.

0082With reference to <figref idref="f0014">Fig. 12c</figref>, an exemplary vertical power array 1100c is shown which may for example be incorporated into the wall of a room, mounted onto the side of a cabinet or other vertical surface. The power array 1100c is used for providing moveable power outlets 120d into which a pinned plug connected to a power cable (not shown) may be plugged, for coupling an electric load to an inductive power jack 110 and thereby providing power to the electric load.

0083Two movable power outlets 120d are also shown. Each outlet 120d includes a magnetic anchor 214 which may be of sufficient strength to support the weight of the movable power outlet 120d when coupled to a magnetic snag 212 embedded in the vertical power array 1100c. Such power outlets 120d may thus be freely moved around the vertical power array 1100c and located at any position which is aligned to a pinless power jack 110. Furthermore, although a vertical power array 1100c is shown in <figref idref="f0014">Figure 12c</figref>, it will be apparent that movable power outlets 120d may be coupled to a power array 1100 in any orientation.

0084<figref idref="f0015">Fig. 13</figref> is a flowchart showing a method for transferring an optical signal between a primary unit and a secondary unit via an intermediate layer. The method comprises the following steps: an optical transmitter is incorporated within the secondary unit - step (a); an optical receiver is incorporated within the primary unit - step (b); the optical transmitter transmits electromagnetic radiation of a type and intensity capable of penetrating the surface layer - step (c); and the optical receiver receives the electromagnetic radiation - step (d).

0085It will be appreciated that such a method may be applicable to transmitting a regulation signal for regulating power transfer across an inductive coupling by monitoring at least one operating parameter of said electric load and encoding the monitored parameter data into said optical signal. Similarly, data relating to the presence of an electric load, its power requirements, operating voltage, operating current, operating temperature or the like may be communicated.

0086The scope of the present invention is defined by the appended claims and includes both combinations and sub combinations of the various features described hereinabove as well as variations and modifications thereof, which would occur to persons skilled in the art upon reading the foregoing description.

0087In the claims, the word "comprise", and variations thereof such as "comprises", "comprising" and the like indicate that the components listed are included, but not generally to the exclusion of other components.