Omnidirectional charging interface for wearable computing device

Abstract

A charging interface (300) for a wearable computing device, such as a smartwatch, is described herein. The charging interface may include a housing having an outer surface (310) and electrical contacts (315) flush with the outer surface. The charging interface may also include a magnet (325) disposed within the housing, the magnet coaxially aligned with the electrical contact along an axis (320), where a magnetic field of the magnet is configured to coaxially align an external charging pad (shown in a dashed line) with the electrical contact along the axis.

Description

Technical Field

[0001] The present disclosure relates generally to wearable computing devices and more particularly to an omnidirectional charging interface for a wearable computing device. Background Art

[0002] A smart wearable computing device, such as a smart watch, may include a charging interface for charging the battery of the smart wearable device. Current solutions may be inductive charging solutions or wired charging solutions. In a wired charging solution, the electrical contacts of the charging interface contact the electrical contacts of a charging pad, which provides charge to the smart wearable device (as well as other functionality, such as providing contacts for other electrical sensor components).

[0003] Current wired charging solutions typically include electrical contacts located in a charging recess. When contacting a charging pad, these contacts typically constrain the wearable device to be oriented in only one or two defined directions in order to dock with the electrical contacts located in the recess. Furthermore, the recess may collect unsanitary debris, which may interfere with charging operations and is generally undesirable for maintaining the hygiene of the charging interface, which often contacts the user's skin while the user is wearing the smart wearable device. Summary of the invention

[0004] Aspects and advantages of embodiments of the present disclosure will be set forth in part in the following description, or may be learned from the description, or may be learned through practice of the embodiments.

[0005] In one embodiment, a charging interface for a wearable computing device may be provided. The charging interface may include a housing having an outer surface and electrical contacts flush with the outer surface. The charging interface may also include a magnet disposed within the housing, the magnet coaxially aligned with the electrical contacts along an axis, wherein the magnetic field of the magnet is configured to coaxially align an external charging pad with the electrical contacts along the axis.

[0006] In another embodiment, a wearable computing device may be provided. The wearable computing device may include a charging interface. The charging interface may include a housing having an outer surface and electrical contacts flush with the outer surface. The charging interface may also include a magnet disposed within the housing, the magnet coaxially aligned with the electrical contacts along an axis, wherein the magnetic field of the magnet is configured to coaxially align an external charging pad with the electrical contacts along the axis.

[0007] These and other features, aspects and advantages of various embodiments of the present disclosure will be better understood with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate example embodiments of the present disclosure and, together with the description, serve to explain the relevant principles. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A detailed discussion of the embodiments for those skilled in the art is set forth in this specification with reference to the accompanying drawings, in which:

[0009] Figure 1 A wearable computing device according to some implementations of the present disclosure is depicted.

[0010] Figure 2 A wearable computing device positioned on an external charging pad is depicted in accordance with some implementations of the present disclosure.

[0011] Figure 3A A charging interface according to an implementation of the present disclosure is depicted.

[0012] Figure 3B A charging interface according to another implementation of the present disclosure is depicted.

[0013] Figure 3C A charging interface according to yet another implementation of the present disclosure is depicted.

[0014] Figure 4A Depicted are electrical contacts of a charging interface positioned at the center of an exterior surface of a housing of the charging interface in accordance with implementations of the present disclosure.

[0015] Figure 4B Depicted are electrical contacts of a charging interface offset relative to a center of an exterior surface of a housing of the charging interface according to another implementation of the present disclosure.

[0016] Figure 4C Depicted are electrical contacts of a charging interface for a small form factor smart wearable device positioned at the center of an outer surface of a housing of the charging interface in accordance with implementations of the present disclosure.

[0017] Figure 5A Depicted is a charging footprint of a charging interface having electrical contacts positioned at the center of an exterior surface of a housing of the charging interface, according to some implementations of the present disclosure.

[0018] Figure 5B Depicted is a charging footprint of a charging interface according to some implementations of the present disclosure having electrical contacts positioned offset relative to a center of an exterior surface of a housing of the charging interface according to implementations of the present disclosure.

[0019] Figure 5C Depicted is a charging footprint of a charging interface for a small form factor smart wearable device having electrical contacts positioned at the center of an outer surface of a housing of the charging interface in accordance with implementations of the present disclosure. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are shown in the accompanying drawings. Each example is provided by way of explanation of the present disclosure rather than by way of limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present disclosure without departing from the scope or spirit of the present disclosure. For example, a feature shown or described as part of one embodiment may be used together with another embodiment to produce yet further embodiments. Therefore, the present invention is intended to encompass such modifications and variations within the scope of the appended claims and their equivalents.

[0021] Battery-powered electronic devices that are not self-powered (such as smart wearable computing devices) require a charging mechanism, such as a charging interface, as a component of the device. The charging interface must account for the wearable computing device's biometric sensors, the comfort of wearing the wearable computing device, ingress protection, and hygiene considerations. Additionally, because wearable devices are intended to be worn continuously, wearable computing device charging interfaces should be intuitive (e.g., magnetic and omnidirectional), fast, and reliable. Further, it is desirable to establish a "standard" charging interface that can be used on a range of devices to improve the user's multi-device experience and minimize the impact on the environment. Wearable computing devices vary greatly in form factor, and there are currently no low-profile, intuitive, universal, omnidirectional charging interfaces available.

[0022] Multi-position magnetic charging interfaces exist, but existing solutions typically include 1 to 2 defined orientations, are not omnidirectional, and require a recess on the charging interface. This recess may collect unsanitary debris, which may interfere with the charging operation and is generally undesirable. Coaxial multi-pin charging interfaces also exist; however, these charging interfaces are typically large, require 2 to 4 pins, and are flat interfaces with locating recesses. The attachment mechanism is typically magnetic and may or may not be included as one of the pin contacts. Due to the flat interface and required recess, these solutions are not low-profile universal charging solutions across a range of device form factors.

[0023] Thus, example aspects of the present disclosure are directed to a charging interface for a wearable computing device that includes a coaxial arrangement of components on a surface of the wearable computing device.

[0024] This arrangement of components enables an omnidirectional wired charging attachment experience. For example, because the electrical contacts can be arranged as concentric rings, the electrical contacts can be arranged anywhere on the surface of the charging interface and can be aligned with the charging pad in any direction, rather than being constrained to a predefined alignment axis due to the location of recessed and / or non-concentric circle contacts.

[0025] To maintain contact between the charging interface and the charging pad, and to overcome spring fit and other forces, a magnet is housed within the charging interface and is used to axially align the charging interface with the charging pad, such as to align the charging face with the charging pad along an axis about which the concentric ring electrical contacts are positioned. The magnetic field is designed to concentrate the field strength along a central axis shared by the electrical contacts, the magnet, and the aligned charging pad. Natural deviations from this axis due to regular use can be accommodated in the charging pad design.

[0026] Thus, the magnetic field serves as the primary alignment mechanism for automatically positioning the charging interface relative to the charging pad (e.g., bringing the electrical contacts into contact with the charging pad). The magnets can primarily provide a "featureless" reaction force to overcome the spring contact and maintain the connection between the charging interface and the charging pad. Alignment can then occur along the central axis of the magnetic field. However, one or more side loads may still act to disengage the charger from the magnetic field. The "self-centering" surface curvature of the charging interface (e.g., a charging interface having a spherical or nearly spherical surface) helps increase the required side load needed to move the charging interface away from the charging pad.

[0027] Thus, the charging interface does not require a recess (e.g., a recess in the surface of the charging interface for the electrical contacts to contact the charging pad) to align the charging pad with the charging interface along a predetermined axis. This helps maintain a hygienic, continuous surface of the charging interface that is comfortable on the skin, easy to clean, and maintained over time. Furthermore, the surface of the charging interface can be continuous and does not require any recesses. This means that debris cannot collect in the recesses, which makes the surface more hygienic because there is no debris to accumulate in the recesses.

[0028] To achieve improved positioning and universal design across a range of devices, the electrical contact arrangement can be made along the surface of a sphere or a near-spherical surface, where the spherical axis (or the normal surface axis of the near-spherical surface) is aligned with the connector axis of the electrical contacts, magnets, and charging pad. A near-spherical surface is a surface that deviates slightly from the contour of a perfect sphere, such as a partially convex contour of a surface. A spherical surface allows for a larger surface area for support and allows the location of the electrical contacts to be placed anywhere along the sphere, giving a wide range of placement flexibility and adaptability across a range of devices and device types. For example, to avoid potential magnetic field interference with certain sensors of a wearable computing device, the electrical contacts can be located away from a center position on the charging interface, and alternatively positioned off-center to contact the charging pad away from other sensors that may be included on the underside of the wearable computing device, for example, along with the charging interface.

[0029] Power received from the charging pad through the charging interface may be used to charge a rechargeable battery of the wearable computing device, which in turn provides power to the wearable computing device.

[0030] Now referring to the accompanying drawings, Figure 1 and Figure 2 A wearable computing device 100 according to some implementations of the present disclosure is depicted. As shown, the wearable computing device 100 can be worn, for example, on an arm 102 (e.g., a wrist) of a user. For example, the wearable computing device 100 can include a band 104 and a housing 110. In some implementations, the housing 110 can include a conductive material (e.g., a metal). In alternative implementations, the housing 110 can include a non-conductive material (e.g., a plastic material, a ceramic material).

[0031] The housing 110 may be coupled to the strap 104. In this manner, the strap 104 may be fastened to the user's arm 102 to secure the housing 110 to the user's arm 102.

[0032] In some implementations, the wearable computing device 100 may include a display screen 112. The display screen 112 may display content (e.g., time, date, biometrics, etc.) for a user to view. In some implementations, the display screen 112 may include an interactive display screen (e.g., a touch screen or a touch-free display screen). In such implementations, a user may interact with the wearable computing device 100 via the display screen 112 to control the operation of the wearable computing device 100.

[0033] In some implementations, the wearable computing device 100 may include one or more input devices 114 that can be manipulated (e.g., pressed) by a user to interact with the wearable computing device 100. For example, the one or more input devices 114 may include a mechanical button that can be manipulated (e.g., pressed) to interact with the wearable computing device 100. In some implementations, the one or more input devices 114 may be manipulated to control the operation of a backlight (not shown) associated with the display screen 112. It should be understood that the one or more input devices 114 may be configured to allow a user to interact with the wearable computing device 100 in any suitable manner. For example, in some implementations, the one or more input devices 114 may be manipulated by a user to navigate content displayed on the display screen 112 (e.g., one or more menu screens).

[0034] The wearable computing device 100 is charged by docking with a charging pad 200. The charging pad 200 may be an inductive charging pad, or may be a conductive charging pad for charging a battery of the wearable computing device 100. To receive a charge from the charging pad, the wearable computing device 100 may include a charging interface, such as the one described below. FIG. 3A to FIG. 3C , FIG. 4A to FIG. 4C and FIG. 5A to FIG. 5CIn some embodiments, the charging interface can be disposed on the underside of the housing 110 (e.g., on the side of the housing 110 that contacts the user's arm 102) and configured to contact the charging pad 200 to receive charge from the charging pad 200 and charge the battery of the wearable computing device 100.

[0035] Figure 3A A charging interface 300 according to an implementation of the present disclosure is depicted. The charging interface 300 includes a housing 305 having an outer surface 310. In some embodiments, the housing 305 may include a conductive material (e.g., a metal). In alternative implementations, the housing 305 may include a non-conductive material (e.g., a plastic material, a ceramic material). The housing 305 may be coupled to the housing 110 of the wearable computing device 100, or may be a component of the housing 110 of the wearable computing device 100 (e.g., may form a continuous housing as part of the housing 110).

[0036] In some embodiments, the outer surface 310 can be a spherical or nearly spherical surface (eg, without dimples, notches, or other indentations or holes interrupting the surface).

[0037] The charging interface 300 also includes one or more electrical contacts 315 that are positioned such that the electrical contacts 315 are flush (i.e., not recessed or raised) with the outer surface 310 (e.g., not recessed or otherwise recessed into the outer surface 310). In this manner, the outer surface 310 can be a continuous, uninterrupted surface. The one or more electrical contacts 315 include one or more conductors that can receive a charge from an external charging pad (such as the charging pad 200) by contacting corresponding conductors of the external charging pad. In some embodiments, the one or more electrical contacts 315 can be used exclusively for charging the wearable computing device 100. In other embodiments, the one or more electrical contacts 315 can be used for one or more other functions, such as operating as both a charging contact and a skin electrode for monitoring vital signs of the wearer of the wearable computing device 100.

[0038] Having one or more electrical contacts 315 flush with the outer surface 310 is advantageous because, with recessed electrical contacts, debris may collect in the recesses. Having one or more electrical contacts 315 flush with the outer surface 310 helps maintain a sanitary, continuous outer surface 310 of the charging interface 300 that is comfortable on the skin and can be cleaned and maintained over time. In addition, because the surface of the charging interface 300 is continuous and does not require any recesses, debris cannot collect in the recesses, which makes the outer surface 310 more sanitary than a surface that includes recesses because the absence of debris to accumulate in the recesses makes the outer surface 310 easier to clean and maintain over time.

[0039] In some embodiments, the one or more electrical contacts 315 may include a plurality of electrical contacts arranged as a group of concentric rings having a common shared center point on the outer surface 310. For example, in some embodiments, the common shared center point may be a point along the axis 320 of the charging interface 300. For example, if the outer surface 310 is spherical in shape, the axis 320 may be the spherical axis of the outer surface 310. In another example, if the outer surface 310 is approximately spherical in shape, the axis 320 may be the normal surface axis.

[0040] In some embodiments, axis 320 can be positioned at a center point of charging interface 300. In other embodiments, axis 320 can be positioned off-center relative to a center point of charging interface 300. Due to the spherical or nearly spherical nature of outer surface 310, one or more electrical contacts 315 and axis 320 can be positioned at any point on outer surface 310 while still allowing charge to be transferred between one or more electrical contacts 315 and a charging pad to which charging interface 300 is coupled. For example, in Figure 3B , axis 320 is positioned off-center relative to a center point of charging interface 300. By positioning axis 320 off-center, charging interface 300 can be brought into contact with a charging pad while also keeping sensitive sensors, such as biometric sensors, away from the connection point between one or more electrical contacts 315 and the charging pad, and allowing wearable computing devices 100 of different types and sizes to use charging interface 300 to engage with a universal charging pad (e.g., a charging pad that is intended to dock with any size or type of wearable computing device 100).

[0041] The charging interface 300 may also include a magnet 325. The magnet 325 generates a magnetic field that is used to align and contact one or more electrical contacts 315 with the external charging pad. For example, the magnet 325 can be selected so that the magnetic field generated by the magnet 325 concentrates the magnetic field strength along a central axis (such as along axis 320). The natural deviation from the central axis due to frequent use of the charging interface 300 can be accommodated by the design of the external charging pad.

[0042] The magnetic field generated by the magnet 325 serves as the primary alignment mechanism for aligning the one or more electrical contacts 315 with the external charging pad, and the primary mechanism for maintaining contact between the one or more electrical contacts 315 and the external charging pad. In some embodiments, the magnet 325 is disposed within the housing 305 so that the magnet 325 is coaxially aligned with the center point of the one or more electrical contacts 315 along the axis 320. In turn, the magnetic field generated by the magnet 325 coaxially aligns the magnet 325, the one or more electrical contacts 315, and the external charging pad. Thus, the one or more electrical contacts 315 can be aligned with the contacts of the external charging pad and contact the contacts of the external charging pad without requiring a recess on the outer surface 310 of the housing 305, which enables the outer surface 310 to be a continuous surface that can be kept sanitary (free of debris) because the outer surface 310 can be easier to clean. Additionally, at least in part because the outer surface 310 of the charging interface 300 is a continuous surface (i.e., there is no recess for the electrical contacts 315), the wearable computing device can be more comfortable on the user's skin.

[0043] The charging interface 300 can be adapted to a variety of wearable computing devices 100 having various form factors. For example, the wearable computing device 100 can be a smaller or narrower smart wearable device, such as Figure 3C Even with a smaller form factor for working with a smaller smart wearable device, the charging interface 300 can still be implemented as a continuous spherical or approximately spherical outer surface 310, and has one or more electrical contacts 315 coaxially aligned with the magnet 325 along the axis 320. Therefore, although the form factor of the smart wearable device is smaller, the charging interface 300 can still use the magnet 325 and the one or more electrical contacts 315 to enable the smart wearable device to dock with a universal charging pad.

[0044] Figure 4AOne or more electrical contacts 315 of the charging interface 300 are depicted positioned at a center point 400 of the outer surface 310 of the charging interface 300 according to an implementation of the present disclosure. The one or more electrical contacts 315 may include a plurality of concentric ring contacts positioned around the center point 400 of the outer surface 310, the plurality of concentric ring contacts being coaxially aligned with the magnet 325 along an axis 320 (through the center point 400), as shown in FIG. Figure 3A shown.

[0045] Figure 4B One or more electrical contacts 315 of the charging interface 300 are depicted offset relative to a center point 400 of the outer surface 310 of the charging interface 300 according to another implementation of the present disclosure. As shown, the one or more electrical contacts 315 may be positioned closer to the perimeter of the outer surface 310 than at the center of the outer surface 310. Such positioning of the one or more electrical contacts 315 may be advantageous because the housing 105 of the wearable computing device 100 may contain various sensors that are sensitive to magnetic fields, such as biometric sensors, and positioning the one or more electrical contacts 315 away from the center of the outer surface may allow the magnet 325 to be used as a primary alignment mechanism for the charging interface 300 and an external charging pad without interfering with these sensors on the wearable computing device 100.

[0046] Figure 4C One or more electrical contacts 315 of a charging interface 300 positioned at a center 400 of an outer surface 310 of the charging interface 300 for a small form factor smart wearable device according to an implementation of the present disclosure are depicted. As described above, the one or more electrical contacts 315 may include a plurality of concentric ring contacts positioned around the center point 400 of the outer surface 310, the plurality of concentric ring contacts being coaxially aligned with a magnet 325 along an axis 320 (through the center point 400), as shown in FIG. Figure 3C In some embodiments, one or more electrical contacts 315 may be positioned near the perimeter of outer surface 310 rather than being positioned around center point 400 .

[0047] FIG. 5A to FIG. 5C Depicted are charging footprints 500 , 505 , and 510 of charging interface 300 , according to some implementations of the present disclosure.

[0048] Each charging footprint shows how a different charging pad docks with the charging port. Figure 5A, charging footprint 500 may be associated with a large charging pad that is aligned with one or more electrical contacts 315 along axis 320 at center point 400 of outer surface 310 via magnet 325, such that the charging pad docks the one or more electrical contacts 315 with its own electrical contacts and also docks with the portion of outer surface 310 shown by the large charger footprint. A small charging pad may also dock its own electrical contacts with one or more electrical contacts 315 aligned along axis 320 at center point 400, while also docking with a smaller portion of outer surface 310 as shown by the small charger footprint.

[0049] exist Figure 5B In the charging footprint 505 shown in FIG. 5 , the large charging pad is aligned with one or more electrical contacts 315 by magnets 325 along axis 320 at a location closer to the perimeter of the outer surface 310. In this case, a portion of the large charging pad is docked with a portion of the outer surface 310, and a second portion of the charging pad is not docked with the outer surface 310, as shown in the large charger footprint. Similarly, the small charging pad (shown by the small charger footprint) has a portion that docks with the outer surface 310 and a portion that does not dock with the outer surface 310.

[0050] exist Figure 5C , a smaller form factor wearable computing device and associated charging interface 300 are shown. A portion of a large charging pad may interface with the entirety of, or a portion approximately the size of, the entirety of the exterior surface 310 (as shown in the large charger footprint), while a smaller charging pad may interface with only a smaller portion of the exterior surface 310 (as shown in the small charger footprint).

[0051] The different charging footprints illustrate the ability of the charging pad to couple to the charging interface 300 in a variety of different configurations. In addition, the charging interface 300 can accommodate charging pads of various sizes because the placement of the continuous outer surface 310 and one or more electrical contacts 315 on the outer surface 310 allows the charging pad to be oriented in a variety of different orientations relative to the charging interface 300, such as FIG. 5A to FIG. 5C 315 . This is due in part to the placement of the magnet 325 relative to the electrical contacts 315 . The different charging footprints also illustrate the cross-compatibility of wearable computing devices with the charging interface 300 . As long as the charging interface 300 has the same curvature (e.g., a spherical or approximately spherical surface), the mating curvature between the charging pad and the charging interface 300 is the same between any two charging pad-charging interface 300 pairs. Therefore, the charging interface 300 can be used with any charging pad designed to contact the charging interface 300, regardless of the wearable computing device 100 to which the charging interface 300 is coupled.

[0052] Although the present subject matter has been described in detail with respect to various specific example embodiments of the present subject matter, each example is provided by way of explanation rather than limitation of the present disclosure. Those skilled in the art, after understanding the foregoing, may easily produce changes, variations, and equivalents of such embodiments. Therefore, the present disclosure does not exclude such modifications, variations, and / or additions to the present subject matter that would be readily understood by those of ordinary skill in the art. For example, a feature shown or described as part of an embodiment may be used together with another embodiment to produce yet further embodiments. Therefore, the present disclosure is intended to cover such changes, variations, and equivalents.

[0053] The terms used herein are used to describe example embodiments and are not intended to limit and / or constrain the present disclosure. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are also intended to include the plural forms. In the present disclosure, terms such as "including", "having", "comprising", etc. are used to specify features, numbers, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more of the features, elements, steps, operations, elements, components, or combinations thereof.

[0054] It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements, the elements are not limited by these terms. Instead, these terms are used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, a first element may be referred to as a second element, and a second element may be referred to as a first element.

[0055] It will be understood that when an element is referred to as being “connected” to another element, the expression encompasses examples of being directly connected or directly coupled as well as being connected or coupled with one or more other elements interposed therebetween.

[0056] The term "and / or" includes a combination of multiple related listed items or any of the multiple related listed items. For example, the scope of the expression or phrase "A and / or B" includes the item "A", the item "B" and the combination of the items "A and B".

[0057] In addition, the scope of the expression or phrase "at least one of A or B" is intended to include all of the following: (1) at least one of A, (2) at least one of B, and (3) at least one of A and at least one of B. Likewise, the scope of the expression or phrase "at least one of A, B, or C" is intended to include all of the following: (1) at least one of A, (2) at least one of B, (3) at least one of C, (4) at least one of A and at least one of B, (5) at least one of A and at least one of C, (6) at least one of B and at least one of C, and (7) at least one of A, at least one of B, and at least one of C.

Claims

1. A charging interface for a wearable computing device, the charging interface comprising: a housing having an outer surface; an electrical contact, the electrical contact being flush with the outer surface; A magnet is disposed within the housing, the magnet being coaxially aligned with the electrical contacts along an axis, wherein a magnetic field of the magnet is configured to coaxially align an external charging pad with the electrical contacts along the axis.

2. The charging interface of claim 1, wherein the electrical contacts comprise a plurality of conductors arranged as a plurality of concentric rings. 3 . The charging interface of claim 2 , wherein the plurality of concentric rings have a common center point at the axis.

4. The charging device interface according to any one of claims 1 to 3, wherein the outer surface is a spherical surface.

5. A charging interface according to any one of the preceding claims, wherein the axis is normal to the outer surface.

6. A charging interface according to any preceding claim, wherein the axis connects the centre of the magnet with the centre of the electrical contact.

7. A charging interface according to any of the preceding claims, wherein the magnet is aligned coaxially with the electrical contacts along the axis and is designed so that its magnetic field holds an external charging pad resting against the outer surface in a charging position relative to the electrical contacts.

8. The charging interface of any one of the preceding claims, wherein the charging interface is configured to receive power from the external charging pad through the electrical contacts, and wherein the charging interface is configured to provide the power to a rechargeable battery of the wearable computing device.

9. A charging interface according to any preceding claim, wherein the electrical contact is provided at the centre of the outer surface.

10. A charging interface according to any preceding claim, wherein the electrical contacts are located closer to the periphery of the outer surface than to the centre of the outer surface.

11. A wearable computing device comprising: A charging interface, the charging interface comprising: a housing having an outer surface; an electrical contact, the electrical contact being flush with the outer surface; A magnet is disposed within the housing, the magnet being coaxially aligned with the electrical contacts along an axis, wherein a magnetic field of the magnet is configured to coaxially align an external charging pad with the electrical contacts along the axis.

12. The wearable computing device of claim 11, wherein the electrical contacts comprise a plurality of conductors arranged as a plurality of concentric rings.

13. The wearable computing device of claim 12, wherein the plurality of concentric rings have a common center point at the axis.

14. The wearable computing device of any one of claims 11 to 13, wherein the outer surface is a spherical surface.

15. The wearable computing device of any one of claims 11 to 14, wherein the axis is normal to the outer surface.

16. The wearable computing device of any one of claims 11 to 15, wherein the axis connects a center of the magnet with a center of the electrical contact.

17. The wearable computing device of any one of claims 11 to 16, wherein the magnet is aligned coaxially with the electrical contacts along the axis and is designed such that its magnetic field holds an external charging pad resting against the outer surface in a charging position relative to the electrical contacts.

18. The wearable computing device of any one of claims 11 to 17, wherein the charging interface is configured to receive power from the external charging pad through the electrical contacts, and wherein the charging interface is configured to provide the power to a rechargeable battery of the wearable computing device.

19. The wearable computing device of any one of claims 11 to 18, wherein the electrical contact is disposed at a center of the outer surface.

20. The wearable computing device of any one of claims 11 to 19, wherein the electrical contacts are positioned closer to a perimeter of the outer surface than to a center of the outer surface.

21. A charging system, comprising: A wearable computing device according to any one of claims 11 to 20; and a charging pad for transferring power to at least one rechargeable battery of the wearable computing device via the charging interface when the wearable computing device is placed at the charging pad.

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