ARTICULATING CORE SEGMENTS AND DEVICES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Application No.

62/372,776, filed August 9, 2016, the contents of which are hereby incorporated by reference.

TECHNICAL FIELD

[0002] This relates to electric transformers, and more specifically to split-core transformers, that may be suitable for use in mobile electronic devices.

BACKGROUND

[0003] PCT Publication No. WO 201 5/070321 , the contents of which are hereby incorporated by references, discloses portable computing devices that may be electrically and mechanically interconnected for interoperability. In some embodiments, these devices may be spatially arranged relative to each other in numerous configurations.

[0004] Allowing flexible interconnection, signal and power transfer between these types of devices remains a challenge.

[0005] Conceivably, signals and energy may be inductively transferred between the devices.

[0006] However, there remains a need for an effectively coupling mechanism. In particular, new transformers that may be used in coupling such devices are desirable. SUMMARY

[0007] According to an aspect, there is provided a split-core transformer comprising a first core segment formed of magnetic material, this first core segment having a central part, and top and bottom end parts on either side of the central part and geometrically distinct from the central part, each of the top and bottom end parts of the first core segment having at least one connection face; a second core segment formed of magnetic material, this second core segment having a central part, and top and bottom end parts on either side of the central part and

geometrically distinct from the central part, each of the top and bottom end parts of the second core segment having at least one connection face. The connection faces of the top and bottom end parts of the first core segment contact respective connection faces of the top and bottom end parts of the second core segment to form a magnetic circuit. One of the at least one connection faces of the top end part and the bottom end part of the first core segment are each rounded to allow the first core segment to articulate relative to the second core segment while

maintaining the magnetic circuit.

[0008] According to another aspect, there is provided an electronic device comprising: a casing, having a lengthwise extending edge having a rounded outer surface; a split-core transformer segment comprising a connection face for interconnecting with a complementary split-core transformer segment to establish a magnetic circuit to transfer electric energy from or to said electronic device. The split core transformer segment is arranged within the casing along the edge, and the connection face is rounded and conforms in shape to the rounded outer surface of the casing. This allows the split-core transformer segment to maintain the magnetic circuit as the electronic device is articulated about the edge.

[0009] Other features will become apparent from the drawings in conjunction with the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the figures which illustrate example embodiments,

[0011] FIG. 1 is a perspective view of an electronic device, exemplary of an embodiment;

[0012] FIG. 2 is a block schematic diagram of the device of FIG. 1 ;

[0013] FIGS. 3-5 are perspective views of devices of the type of FIG. 1 ,

interconnected in different configurations;

[0014] FIG. 6 is a perspective view of a split-core transformer segment, exemplary of an embodiment;

[0015] FIGS. 7A-7D are plan views of the split-core transformer segment of FIG. 6;

[0016] FIGS. 8A-8E are perspective and plan views of a split-core transformer formed from core segments of FIGS. 6 and 7A-7D, in a first configuration;

[0017] FIGS. 9A-9E are perspective and plan views of a split-core transformer formed from core segments of FIGS. 6 and 7A-7D, in a second configuration;

[0018] FIG. 10 is a schematic diagram of the split-core transformer of FIGS. 8A- 9E;

[0019] FIGS. 11 A-11 B are functional block diagrams showing the

interconnection of split-core transformer segments in the devices of FIGS. 2-5;

[0020] FIGS. 12A-12E are diagrams of an alternate split-core transformer segment; and

[0021] FIGS. 13A-13E are diagrams of a further alternate split-core transformer segment. DETAILED DESCRIPTION

[0022] FIG. 1 depicts an electronic device 14 exemplary of an embodiment.

[0023] Device 14 include a housing 16 defined by contiguous external surfaces. Lateral edges 18 interconnect the front and rear sides of housing 16. Lateral edges 18 are rounded. As used herein rounded is intended to describe edges 18 as at least slightly curved, and not completely orthogonal to the front and rear sides of housing 16. Rounded may, for example, encompass curved, circular, elliptical, chamfered, filleted, facetted or beveled edges.

[0024] Device 14 may be any electronic device that interface with another identical or similar electronic device and provide complementary functions, as for example disclosed in United States Patent No. 9,312,633. A touch display 50 may be formed on housing 16, on one of its faces. As depicted, device 14 may be a smartphone.

[0025] Example device 14 may alternatively be, without limitation, a cellular phone, cellular smart-phone, wireless organizers, pagers, personal digital assistant, computer, laptop, handheld wireless communication device, wirelessly enabled notebook computer, portable gaming device, tablet computers, televisions, monitors, thermostats, speakers or any other portable electronic device with processing and communication capabilities. In at least some embodiments, devices as referred to herein can also include, without limitation, peripheral devices such as displays, printers, touchscreens, projectors, digital watches, cameras, digital scanners and other types of auxiliary devices that may communicate with another computing device.

[0026] Device 14 includes magnetic connectors 20 at each corner of its housing, so that multiple devices 14 may be used together. An example of possible magnetic connector 20 is described in International Patent Application Publication No. WO 201 5/070321 and United States Patent Application No. 14/91 8,177, the contents of which are incorporated herein by reference. Each connector 20 allows mechanical coupling of adjacent devices 14 and, optionally, electrical connection.

[0027] Each device 14 may further include at least one split-core transformer segment 100 (simply referred to as core segment or split-core segment, herein), exemplary of embodiments along each lateral edge 18, schematically depicted in FIGS. 11A-11 C, and further described below. In the depicted embodiment, device 14 includes at least one split core segment 100 on each edge 18 at the same location along the edge 18.

[0028] Split-core segments 100 installed within an example device 14 are illustrated in outline in FIGS. 11 A-11 C. As illustrated, the shape of split-core segment 100 conforms to the shape of edge 18 of device 14. In particular, at least one face of split core segment is rounded to conform to the rounded exterior shape of edge 18 of device 14. This face may be complementary to the interior of edge 18. Split-core segment 100 may, for example, be installed in the middle of the length of edge 18. It may be disposed in numerous ways known to those of ordinary skill - for example using glue, mechanical fasteners, nibs on the interior of housing 16, or otherwise. Other locations will be apparent to those of ordinary skill. Alternatively, multiple split-core segments could be located along each edge 18.

[0029] A simplified example hardware architecture of device 14 is further detailed in FIG. 2. As illustrated, device 14 includes a processor 40, processor readable memory 42, and input/output (I/O) interface 44; and a network interface 46, all interconnected by way of one or more suitable interconnection buses.

Device 10 may further include touch display 50 (FIG. 1 ) formed in housing 16, on one of its faces. Connectors 20 and split-core segments 100 may be in

communication with processor 44 by way of I/O interface 44.

[0030] Processor 40 may be a suitable computer processing subsystem and may include a numerical processor having multiple cores, and a graphics processor (not specifically illustrated). In embodiments, processor 40 may include a RISC processor having an ARM based architecture, and may for example, be a suitable mobile processor manufactured by Qualcomm, Mediatek, Apple or the like. In other embodiments, processor 40 may be based on the x86 architecture. In yet other embodiments, processor 40 may be a custom processor.

[0031] Touch display 50 may, for example, be capacitive display screens that include a touch sensing surface. Such a display may be integrated as a single component. Alternatively, touch display 50 may include suitably arranged separate display and touch components. Touch display 50 may be adapted for sensing a single touch, or alternatively, multiple touches simultaneously. Touch display 50 may sense touch by, for example, fingers, a stylus, or the like. Touch display 50 may return the coordinates of any touch or touches for use by a process or device 10. Likewise, touch display 50 may be used to display pixelated graphics - in the form of computer rendered graphics, video and the like.

[0032] FIGS. 3-5 depict a device system 12 formed of by interconnecting two electronic devices 14-1 , 14-2, like electronic device 14 of FIG. 1. Devices 14-1 and 14-1 will be individually and collectively referred to as device(s) 14.

[0033] In one example, devices 14 may be smartphones, or one may be a smartphone and the other a peripheral device (e.g., a speaker, a keyboard, a display screen, a camera). In another example, one device may be a touchscreen enabled device and the other a type of communication device (e.g., a router, alarm panel, home automation interface, thermostat, or the like) for connection to other devices. As will be apparent, other types of electronic devices 14 can be envisaged that benefit from interconnection and interoperability.

[0034] Further, in some embodiments, devices 14 may be of the same type - generally identical in structure and components. In other embodiments exemplified below, devices 14 (or a similar device) may interoperate with other different yet compatible devices, in a manner exemplified herein.

[0035] Similarly, although two interconnected devices 14-1 , 14-2 are shown in FIG. 3, multiple (e.g., three or more) interconnected devices can be envisaged having alternate connector configurations, layout, and position and alternate size and layout of device 14. Other geometries of devices 14, for example, generally rectangular with rounded corners, oval, or rounded in shape, may be contemplated by a person skilled in the art. Example devices having different geometries are for example illustrated in United States Patent Application No. 1 5/013,750, the contents of which are hereby incorporated by reference.

[0036] In some embodiments, a composite display formed as a larger interconnected screen, allows input to be received from one or more interconnected touch display 50 of another device 14.

[0037] As shown in FIG. 3 devices 14 may be arranged side by side with a pair of edges 18, e.g. lateral surfaces of edges, placed next to each other, typically when in use, or, as shown in FIG.4 in a stacked configuration with a different pair of surfaces, e.g. front and back surfaces, next to each other.

[0038] As noted, each device 14 includes magnetic connectors 20 at each corner of its respective housing 16, so that the devices may be used together. For example, two devices may be placed side-by-side, with lateral edges 18 abutting and connectors 20 engaged with one another, as shown in FIG. 3. Devices 14 may be used in such a configuration, for example, to cooperatively render or display content using displays of both devices 14, as for example disclosed in PCT

Publication No. WO 201 5/070321 .

[0039] Conveniently, as devices 14 have core portions 100 on either edge 18, two identical or complementary devices 14 can be connected along either of its edge 18 in a side by side relationship, as for example illustrated in FIG. 3. Two core portions 100 (one on each device 14-1 and 14-2) are thus in adjacent relationship to form a transformer as detailed below.

[0040] Devices 14 may also be placed on top of one another, so that a top or bottom surface of one device abuts a top or bottom surface of another device as shown in FIG 3. Such configuration may, for example, be used where one device 14-1 is a smartphone and another device 14 is a memory storage device.

[0041] In some embodiments, devices 14-1 and 14-2 may be placed side-by- side and articulated or pivoted relative to one another, about an edge 18, and thus axis 15 as shown in FIG. 3. Such movement of devices may cause changes in functioning modes of the devices 14.

[0042] In the abutting configurations of FIGS. 3-5, core segments 100 of adjacent devices are aligned by virtue of their relative position to connectors 20 on edges 18, and are thus also adjacent to each other. Core segments 100 of two adjacent devices 14 may thus form a transformer 150, as for example schematically illustrated in FIGS. 8A-8E; 9A-9E; and 11A-11 C, to allow signals and/or electrical power/energy to be transferred between two adjacent devices 14.

[0043] In a front-to-back (or back-to-back) relationship, as exemplified in FIG. 4, two core segments 100 on device 14-1 are in proximity with two core segments 100 on device 14-2, effectively creating two transformers 150. In this way, two split- core transformer segments 100 of device 14-1 are configured for concurrent connection to complementary two split-core transformer segments 100 on the other device. This may allow the transfer of double the power, or twice the signals between devices 14-1 and 14-2, than in the side-by-side configuration of FIG. 3.

[0044] In some embodiments, core segments 100 may be exposed through a housing 16 of device 14. In this case, when two devices 14-1 and 14-2 are connected, core segments 100 of the respective devices may directly touch. This improves magnetic coupling between two adjacent core segments 100.

[0045] A USB 2.0/3.0 bus may also be established through the electrical connection made by connectors 20 of adjacent connectors. Optionally, devices 14 may communicate wirelessly or through core segments 100, in which case connectors 20 need not establish an electrical connection through connectors 20.

[0046] Conveniently, lateral edges 18 along with connectors 20 may form a hinge around which electronic devices 14 can articulate relative to one another along the rounded lateral edges 18 when coupled (about axis 15), allowing switching from one of the configurations shown in FIGS. 3-5 to another, without interrupting the mechanical or electrical connection. Split-core segments 100 may be disposed within housing 16 of device 14. In this case, when two devices 14 are connected, split-core segments 100 are separated by at least the housing thickness, e.g., a few millimetres. This is schematically illustrated in FIGS. 11 A- 11 C. Split-core segment 100 is shaped such that magnetic coupling between the split-core segments 100 may be improved by pivoting devices 14 to change their relative orientation (e.g., when changing from the configuration of FIG. 3 to FIG. 4).

[0047] Devices 14 may be interconnected during operation to transmit data to one another. During operation, one e.g. device 14-1 may act as a host and the other may act as a slave. In some embodiments, the host-slave relationship may switch depending on the function or functions being performed. Therefore, each of the devices may include a hub for managing data flow with a host-slave relationship in either direction, as for example disclosed in United States Patent No. 9,529,758.

[0048] Split-core transformer segments 100 of devices 14 are further depicted in FIGS. 6, and 7A-7D, removed from devices 14. Split-core segments 100 of two adjacent devices 14 are depicted in FIGS. 8A-8E and 9A-9E, completing a transformer 150. A flux model of transformer 150 is depicted in FIG. 10.

[0049] Split-core transformers for power transmission is generally known; see, e.g., Dwayne Servidio and Anthony Bruno, "Modeling of Split-Core Transformers for Power Transmission", presented at the International Magnetics Conference, Stockholm, Sweden, 13-1 6 April 1993,

(httD://www.dtic.mil/dtic/tr/fulltext/u2/a282782.pdf), hereinafter referred to as "Servidio", the contents of which are hereby incorporated herein by reference.

[0050] In a split-core transformer, a transformer core may be formed of two split- core segments that may be placed next to each other to complete a transformer. One split-core segment carries a primary winding while another split-core segment carries secondary windings. A varying AC current in the primary winding creates a varying magnetic flux in the core, which results in a varying magnetic field at the secondary windings. This varying magnetic field induces a current in the secondary windings.

[0051] In this way, power may be transferred from one segment 100 of one device 14 to another segment 100 of an adjacent device 14 that completes transformer 150, e.g., when the core segments 100 are touching or when the core segments are spaced by a gap. As explained in Servidio, efficiency of power transfer may decrease when the distance between segments is increased.

[0052] As illustrated in FIGS. 6 and 7A-7D, an exemplary split-core segment 100 includes a central part 104 and geometrically distinct end parts 106a and 106b, exemplary of an embodiment. In the depicted embodiment end parts 106a and 106b may be considered generally bulbous and are larger than central part 104.

[0053] In this embodiment, windings 120 of each split-core segment 100 may include helically wound wire - e.g. 40 AWG magnet wire (enamel insulated copper wire), e.g., having approximately 1 0-300 (or more) total turns in multiple (e.g. three or four) layers - wound about a winding axis that extends along the length of central part 104.

[0054] In particular, end parts 106a, 106b each includes several exposed faces. In the depicted embodiment five such faces are exposed for each end part 106a, 106b. Specifically, faces 110a, 111a, 112a, 113a, 114a of end part 106a are exposed. Faces 110b, 111 b, 112b, 113b, 114b of end part 106b are exposed. Face 114a/114b lie in planes generally perpendicular to the plane of the lengthwise axis of central part 104 (and thus the winding axis of windings 120). Faces

111a/111 b; 112a/112b; 113a/113b are generally flat, and rectangular and are outward facing (i.e. away from the lengthwise extent of core segment 100). Faces 110a, 111a, 112a, 113a extend generally perpendicular from face 114a/114b. As well, face 113a is further perpendicular to face 112a and 111 b. Faces 113a and 114a (and faces 113b and 114b) are also generally perpendicular to each other.

[0055] Face 110a is rounded or curved and connects face 112a to face 111 a. The curvature of face 110a may thus depend on the relative length of face 112a and 111a. It is also outward facing. At least one of these exposed faces serves of each end part 106a/106b as an abutment or connection face.

[0056] Each end part 106a/106b and central part 104 may be formed of a ferromagnetic material such as nickel, iron, etc., or a suitable alloy. In some specific embodiments, each end part 106a/106b may be formed of a cobalt-iron alloy (e.g., Hiperco50), a nick-iron alloy (e.g., EFI Alloy 50), a low carbon steel alloy (e.g., 1080 steel), a Magnesium Zinc Ferrites, etc. In some embodiments, the material may be selected to have high magnetic saturation so that a stronger magnetic field may be generated. End parts 106a/106b and central part 104 may be integrally formed.

[0057] FIGS. 7A-7D further illustrate possible dimensions of end part 106a/106b according to an embodiment. As illustrated, faces 113a/113b may have dimensions 4.3 mm x 5.5mm; faces 112a/112b: 6.3mm x 5.5 mm; and faces

111a/111 b: 3.25mm x 5.5 mm. Central part 104 may be cylindrical having a diameter 3mm and length 6mm.

[0058] Of note, each segment 100 has two distinct sets of connection faces, namely, the set of faces 110a/110b and the set of faces 111 a/111 b. Faces 1 10a/1 10b are rounded and thus well suited for articulation when devices are placed side-by-side (including transition to a stacked configuration) relationship as illustrated in FIGS. 3 and 5. Faces 111 a/111 b (and possibly others) are generally flat and well suited for reducing any gap when devices are stacked, as for example illustrated in FIG. 4.

[0059] In the depicted embodiment of FIGS. 7A-7D, for example, faces

110a/110b, 111 a/111 b and 112a /112b may serve as abutment connector faces to split-core segments 100 and may be brought into contact or proximity in order to form a transformer, as for example transformer 150.

[0060] The space between connection faces of core segments 100 of adjacent devices acts as an air gap.

[0061] As will be appreciated, transformer 150 formed by two adjacent core segments 100 of devices 14-1 and 14-2 (as for example illustrate in FIG. 8A and 8B) establishes a magnetic system in which flux is driven by magnetomotive force (MMF) and guided by material tubes may be evaluated in the same way as an electric circuit in which current is driven by electromotive force (EMF) and guided by material tubes by reducing each segment to a lumped parameter analogous to a resistor. This lumped parameter is known as a reluctance, Jl. The behavior of these materials may be seen directly from Maxwell's equations.

[0062] Ampere's law in magnetoquasistatic form states that

/ Hdl = // ys^which relates the Magnetic Field Strength around a loop to the current contained in the area enclosed by the loop (J is current density), and is the equivalent of Kirchoff's Voltage Law. Gauss' Law for magnetic flux states that j Bds = 0 which is the equivalent of Kirchoff's Current Law.

[0063] It may be illustrated that the flux tube analysis may be modelled as an electric circuit analog in which the magnetic flux φ is analagous to current, the MMF drive Ni is analogous to voltage, and the reluctances Jl are analogous to

resistance.

[0064] This circuit analogy is schematically depicted in FIG. 10. A complicated structure of magnetic steel may thus be analyzed as a network of resistors, each corresponding to a flux tube, or segment of steel that confines flux, having reluctance RCORE- In the case of nonlinear materials, Jl may be extended to become 32(q>) via a μ(Η).

[0065] The geometry of the gap between core segments 100 in transformer 150, including the contours of the cores, determines the reluctance of the gap (RGAP) , and correspondingly the amount of flux that may be passed through the core. To minimize the effect of any peculiar geometry in the airgap, these sections of the split-core segments 100 may be oversized to limit the increase in reluctance associated with the gap.

[0066] The flux density carried in the core is a property of the material. Iron and its alloys carry high flux density, but suffer from losses as frequency increases. Other materials, such as ferrites, have correspondingly-lower flux carrying capacity, but do not have nearly as significant power losses as frequency increases.

[0067] The voltage on a secondary winding (e.g. on, for example winding 120 of core segment 100 of device 14-2) is the product of the number of windings, N, the flux flowing through the core, φ, and the frequency of excitation. Voltage must be sufficient to power electronics on the secondary side. Current is limited by the power loss in the windings, which is inversely proportional to the area of the windings. Optionally, the size of transformer 150 may be minimized, while still meeting the power and efficiency requirements of the transformer.

[0068] As illustrated in FIGS. 9A-9E, in one configuration, faces 112a/112b of each end part 106a/106b of one split-core segment 100 of one device (e.g. device 14-1 ) may be brought into abutment with like face 112a/112b (e.g. device 14-2) of another core segment 100, to complete transformer 150. In a further configuration shown in FIGS. 8A-8E, rounded abutment faces 110a/110b of one split-core segment 100 of one device (e.g. device 14-1 ) may be brought into contact or proximity with like faces on another split-core transformer segment 100 of another device (e.g. device 14-2) to complete a transformer 150.

[0069] Once split-core transformer segments 100 are brought into proximity with each other, a magnetic circuit between windings 120 of the respective core segments 100 is completed, allowing magnetic flux induced, for example by way of a current on windings 120 of one segment 100 to be coupled to windings 120 of the other split-core segment 100. Signals may thus be passed between processor 40 of adjacent devices through the resulting transformer 150. Alternatively, or additionally electric power to power devices may be transferred by way of transformer 150.

[0070] As noted, above the shape of split-core segment 100 conforms to the shape of edge 18 of device 14 as illustrated in FIGS.11 A-11 C. In particular, at least one face 110a/110b of each end part 106a/106b is rounded to conform to the rounded shape of edge 18 of device 14. As noted above, split-core segment 100 may for example be installed in the middle of the length of edge 18. Other locations will be apparent to those of ordinary skill.

[0071] As perhaps best viewed in FIGS. 11 B and 11 C, split-core segments 100 of two devices 14 may be brought into proximity by abutting edges 18 of devices 14, thereby completing forming transformers 150 to allow the transfer of power and signal between devices 14. Core segments 100 meet at their flat, rectangular abutment surfaces 111a/111 b, which reduces spacing between the split-core segments 100. This decreases gap reluctance, and thus leakage inductance, and improves power transmission efficiency.

[0072] Articulation about axis 15/edges 18, as illustrated in FIG. 5 is also possible, while maintaining a magnetic circuit formed by split-core segments 100.

[0073] Notably, the portions of housing 16 that are exterior to each split-core- segment 100 separate split-core segments 100 of devices 14-1 and 14-2 as they are in contact with each other. Housing 16 of devices 14-1 and 14-2 thus fill part of the gap between split-core segments 100, between abutment/connection faces 111 a/111 b or 112a/112b. The reluctance of casings 16 may factor into the gap reluctance between segments 100, as for example modelled in the schematic equivalent of FIG. 9, as part of the gap reluctance (RGAP)-

[0074] Additionally, as one device 14-1 is articulated relative to the other 14-2, on its device edge 18, as for example depicted in FIG. 5, split-core segments 100 are similarly articulated relative to each other, but remain in proximity with each other as illustrated in FIGS. 9A-9E. This allows the magnetic circuit/transformer 150 formed by core segments 100 of devices 14-1 and 14-2 to continue to be completed, allowing power transfer and signal transfer to continue as devices 14-1 and 14-2 are articulated relative to each other. Of interest, the magnetic field that is coupled between adjacent core segments 100 may vary depending on the degree and angle of contact between coupling surfaces 110a/110b, as segments 100 are articulated relative to each other. This may again be modelled as gap reluctance in the schematic equivalent of FIG. 10.

[0075] Ultimately, devices 14 may be articulated so that faces 112a/112b of split-core segments are in abutment, although space further from each other than faces 111 a/111 b in the configuration of FIG. 11 B.

[0076] As such, devices 14 may be operated in a first mode in which abutment faces 111 a/111 b couple magnetic flux between split-core segments 100 with higher power transmission efficiency, and in a second intermediate mode in which rounded abutment faces 110a/110b couple magnetic flux between split-core segments 100 with lower power transmission efficiency as devices 14 are articulated; and in a lowest power transmission mode in which abutment faces

112a/112b couple magnetic flux between split-core segments 100.

[0077] Split-core segments 100 are shaped so that they allow windings 120 to be wrapped around them and remain within the mechanical envelope of their container, as they are articulated about axis 15. Windings 120 may be wrapped around central part 104, and optionally, end parts 106a, and 106b.

[0078] The dimensions of split-core segments 100, and abutment faces (e.g. faces 110a/110b, 112a/112b, 111 a/111 b) allow sufficient flux to flow to transfer across the gap between surfaces 110a/110b and 112a/112b. The dimensions of the split-core segments 100 near the gap between surfaces 110a, 110b/ 112a, 112b may be oversized, relative to central part 106 to compensate for the increase in reluctance caused by the gap geometry.

[0079] As will now be appreciated, the geometry of split-core segments 100 may be varied. In a further embodiment depicted in perspective view in FIG. 12A; in front view in FIG. 12B; in side views in FIGS. 12C and 12D; and in top view in FIG. 12E, split-core segments 100' may include a rounded face 110' on each end part 106', between two opposing generally identically sized rectangular outwardly facing faces 111 ' and 112'. Rounded face 110' may for example be a cylindrical section. Central part 104' may have any suitable cross-section. It may, for example, be round, rectangular or square. Split-core segments 100' may brought into proximity using faces 111 ', 112' or 113' as connection faces as illustrated in FIGS. 12F-12G to form transformer 150'. As two core segments 100' are articulated relative to each other, faces 110' may serve as connection faces.

[0080] In further embodiments, split-core segments 100", depicted in in perspective view in FIG. 13A; in front/side view in FIG. 13B; and in top view in FIG. 13C, may include end parts 106" that may be cylindrical, with a single round outer surface 110" that may be used as an abutment or connection surface to form a transformer 150" (FIGS. 13D-13E). Unlike split-core segments 100 and 100', split- core segments 100" are shaped to provide substantially constant magnetic coupling between split-core segments 100" as devices 14 having split-core segments 100" in place of split-core segments 100 are articulated or pivoted relative to one another about axis 15, as for example illustrated in FIGS. 13D and 13E.

[0081] Other geometries for split-core segments having suitable

abutment/connection faces will now be apparent to those of ordinary skill.

[0082] Of course, the above described embodiments are intended to be illustrative only and in no way limiting. The described embodiments are susceptible to many modifications of form, arrangement of parts, details and order of operation. The invention is intended to encompass all such modification within its scope, as defined by the claims.