Patent ID: 12261449

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the disclosed concepts. As part of this description, some of this disclosure's drawings represent structures and devices in block diagram form for sake of simplicity. In the interest of clarity, not all features of an actual implementation are described in this disclosure. Moreover, the language used in this disclosure has been selected for readability and instructional purposes, has not been selected to delineate or circumscribe the disclosed subject matter. Rather the appended claims are intended for such purpose

Various embodiments of the disclosed concepts are illustrated by way of example and not by way of limitation in the accompanying drawings in which like references indicate similar elements. For simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the implementations described herein. In other instances, methods, procedures and components have not been described in detail so as not to obscure the related relevant function being described. References to “an,” “one,” or “another” embodiment in this disclosure are not necessarily to the same or different embodiment, and they mean at least one. A given figure may be used to illustrate the features of more than one embodiment, or more than one species of the disclosure, and not all elements in the figure may be required for a given embodiment or species. A reference number, when provided in a given drawing, refers to the same element throughout the several drawings, though it may not be repeated in every drawing. The drawings are not to scale unless otherwise indicated, and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure.

FIGS.2A and2Billustrate a wireless (inductive) power transfer arrangement including a size mismatch between the PTx winding103and the PRx winding105. In the illustrated arrangement, PTx winding103has a larger diameter than PRx winding105. In other circumstances, not illustrated, the reverse could be true. In the profile view ofFIG.2B, flux lines202illustrate an exemplary flux path associated with driving PTx winding103(shown in plan view inFIG.2A) in a counterclockwise direction. As can be seen inFIG.2B, some of flux lines202pass through PRx winding105. This portion of the flux may be thought of effectively coupled to the PRx device. However, some of the flux lines202do not pass through PRx winding105, but rather, reach metallic components of PRx device104(i.e., the aforementioned “friendly metal”), which is denoted by the “X” markings inFIG.2B. To the extent that some of the magnetic flux from103interacts with the friendly metal rather than PRx winding105, the magnetic coupling between PTx and PRx is reduced. This may be at least in part because of the differing sizes of the respective PTx and PRx windings103and105.

One way to address this size mismatch and improve the degree of magnetic coupling between PTx and PRx windings103and105is to provide a flux shielding and/or redirecting accessory between the PTx and the PRx.FIG.3Aillustrates a profile view of such an arrangement, whileFIG.3Billustrates a plan view of such an arrangement. The flux shielding and/or redirecting accessory may include a core300made from ferrite or other ferromagnetic material having suitable magnetic properties, such as sintered ferrite or nanocrystalline sheets. Core300may be dimensioned so as to shield the friendly metal of the PRx104from flux induced by the PTx winding104and/or to effectively redirect some or substantially all of that flux into the PRx winding105.

In the illustrated example having a relatively larger PTx coil103and a relatively smaller PRx coil105, the ferrite core300may be a ring shape having an inner diameter (ID) that generally corresponds to the inner diameter of the PRx coil and an outer diameter (OD) sufficiently large to intercept flux from the PTx coil that would otherwise couple into the friendly metal. By positioning such a core300between, generally parallel to, and substantially overlapping and coaxial with the respective windings, magnetic coupling between the windings103,105may be improved and flux coupling into the friendly metal of the PRx device104may be reduced.

A substantially similar solution can also be implemented in the reverse situation, in which the PRx coil is larger and the PTx coil winding is smaller. Also, as noted above, the shapes of the respective windings and core need not be strictly circular, but could be any closed or substantially closed shape, such that the diameters referenced above could be inner side lengths, major and minor axis lengths, etc. By “substantially closed” shape, it is to be understood that the core could be constructed from two or more segments of magnetic material with relatively smaller (compared to the core size) gaps between the segments. What matters is that core300be positioned and dimensioned so as to reduce undesired flux coupling from the PTx winding103into the friendly metal of PRx device104and/or to enhance flux coupling into PRx winding105. Additionally, although the described embodiment features substantially planar coils and core300, the same principles apply to non-planar windings and non-planar intermediate cores300. In such embodiments, intermediate core300should be shaped, positioned, and dimensioned so as to reduce undesirable flux coupling into so-called “friendly metal” and/or to increase the amount of flux that couples into the PRx winding.

In various other implementations core300dimensionally conforms to the shape of the PTx coil instead of the PRx coil. For example, putting the phone within a case may align ferrite core300with the power transmitting winding103of charging pad102so that the outer diameter of the ferrite core/ring300algins with the diameter of the transmitter winding103, and the inner diameter of the ferrite core/ring300is sized so that the central aperture of structure300allows flux to flow to power receiving window105of the phone104. That is, the inner diameter of the ferrite core/ring300is larger than the inner diameter of the power receiving winding105of the phone104. In some cases, the inner diameter of the ferrite core/ring300is larger than the inner diameter and smaller than the outer diameter of the power receiving winding105.

In various implementations of PTx devices102and PRx devices104, the intermediate device incorporating core300may take a variety of forms. As one example, the PTx102may be a charging mat, PRx104may be an electronic device, such as mobile phone, smart watch, tablet computer, wireless earphone charging case or other device, and the intermediate device incorporating ferrite core300may be an accessory400for the electronic device as illustrated inFIGS.4A(plan view) and4B (profile view). Accessory400may be a case for the mobile phone, a “shim” that can be disposed between the PTx and PRx, or another intermediate device incorporating ferrite core300. Ferrite core300may be disposed in accessory400, with the accessory being designed and dimensioned to appropriately position core300relative to the PRx winding of the PRx device. For example, putting the phone within a case may suitably align ferrite core300with the power receiving winding105of the phone104so that that the inner diameter of the ferrite core/ring300aligns with the outer diameter of the receiver winding105and the annulus of the ferrite core/ring300shields friendly metal of the phone104from the flux induced by PTx winding103of charging pad102.

As illustrated inFIGS.5A-5B,6A-6B, and7A-7B, a case500,600, or700, respectively, may also optionally include one or more mechanisms for assisting a user to align the accessory/phone combination with an external charging device. As but one example, such an accessory, whether a case, shim, or otherwise, may also include one or more magnets that can serve to align the accessory/device combination with a wireless power transmitter and/or receiver device having complementarily arranged magnets. This alignment can assist with aligning the respective coils of the devices as well as aligning the ferrite core300with the PTx winding103and/or PRx winding105. InFIGS.5A and5B, magnet ring502is depicted as being below ferrite ring300, or, in other words, ferrite ring300is disposed between the magnets and the device (e.g., phone, not shown). As in the embodiment ofFIGS.4A and4B, ferrite ring300prevents flux from the transmitter coupling into the “friendly metal” of the device, reducing undesirable power loss and associated heating. Additionally, the magnets of magnet ring502may be segmented to reduce losses. In this embodiment, the accessory may be mechanically positioned and secured to the device (according to various known techniques), and the magnets may be used to assist in attaching and aligning the device/accessory combination to the power transmitting device (e.g., a charging pad, not shown). Additionally, as noted above, and described in greater detail below, ferrite ring300may also be segmented, in which case magnet ring segments and ferrite ring segments may be interspersed as illustrated below with respect toFIG.10.

InFIGS.6A and6B, magnet ring502is depicted as being above ferrite ring300, or, in other words, ferrite ring300is disposed between the magnets and the power transmitting device (not shown, e.g., a charging pad). As in the embodiment ofFIGS.4A-4B and5A-5B, ferrite ring300prevents flux from the transmitter coupling into the “friendly metal” of the device, reducing undesirable power loss and associated heating. Additionally, the magnets of magnet ring502may be segmented to reduce losses. In this embodiment, the accessory (e.g., case or shim) may be magnetically secured (and aligned) to the device (e.g., phone), and the device/accessory combination may be freely positioned with respect to the power transmitting device (e.g., a charging pad, not shown). As above and described in greater detail below, ferrite ring300may also be segmented, in which case magnet ring segments and ferrite ring segments may be interspersed as illustrated below with respect toFIG.10.

InFIGS.7A and7B, magnet ring502is depicted as being substantially in the same plane as ferrite ring300. Exact coplanarity is not required, and may not even be possible depending on the respective heights of the magnets and ferrite core for a given embodiment. As in the embodiments ofFIGS.4A-4B,5A-5B, and6A-6Bdiscussed above, ferrite ring300prevents flux from the transmitter coupling into the “friendly metal” of the device, reducing undesirable power loss and associated heating. Additionally, the magnets of magnet ring502may be segmented to reduce losses. In this embodiment, magnets may be used to secure and position the accessory with respect to the device and/or the power transmitting device (e.g., a charging pad).

InFIG.10, likeFIGS.7A and7B, magnet ring502is depicted as being substantially in the same plane as ferrite ring300. As discussed above, exact coplanarity is not required, particularly in view of the possibility of different respective heights of the magnets and ferrite core for a given embodiment. However, for packaging, it may be helpful for magnet components in ring502and ferrite components in ring300to be arranged such that at least part of these components are co-planar so as to reduce z-height of the resulting accessory. As in the embodiments ofFIGS.4A-4B,5A-5B,6A-6B, and7A-7Bdiscussed above, ferrite ring300prevents flux from the transmitter coupling into the “friendly metal” of the device, reducing undesirable power loss and associated heating. Additionally, the magnets of magnet ring502are segmented into segments “M” to reduce losses and improve manufacturability. Ferrite ring300is likewise segmented into segments “F,” which are interposed between magnet segments “M.” As above, the magnets may be used to secure and position the accessory with respect to the device and/or the power transmitting device (e.g., a charging pad). The relative size of the magnet segments and ferrite segments, both radially and circumferentially, may be adjusted as required to provide a sufficient fastening force as between accessory1000and the device (e.g., phone) and/or power transmitter (by increasing the size of the magnets) and/or to increase the flux shielding/coupling effect (by increasing the size of the ferrite segments). In some embodiments, the relative positioning of the magnet ring segments and ferrite ring segments may be such that the various segments are substantially collinear along the circumference of the respective rings. Depending on the particular dimensions of the ferrite ring segments and magnet ring segments, exact collinearity may not be required or provided, as broad collinearity around the circumference may be appropriate for some applications.

FIG.8illustrates an alternative embodiment of a flux shielding/redirecting accessory801incorporating ferrite core300. Accessory801may be a shim device adapted for positioning, and optionally securing, to the PTx device102itself. (As above, PTx device102may, for example, be a charging mat, charging pad, or other suitable wireless/inductive charging device.) Accessory801may also include mechanical, adhesive, and/or magnetic features802for aligning and/or securing the intermediate device801with respect to the PTx102and the associated PTx winding103. As above, core300should be dimensioned as positioned so as to suitably reduce undesired flux coupling into friendly metal of the PRx device (such as a mobile phone or other electronic device or accessory) and/or to enhance flux coupling into the PRx winding105of the PRx device. As such, it will need to be positioned relative to the PTx winding105such that it intercepts and/or redirects flux that would ordinarily couple into the friendly metal of the PRx device.

FIG.9illustrates further details of embodiments902,904of a flux shielding/redirecting accessory801(FIG.8). In embodiments902and904the PTx device102can include a plurality of transmit coils103, arranged as a DDQ coil. Accessory902,904may be positioned between the PTx device102and the PRx device104(e.g., a mobile phone). Accessory902,904may include a ferrite ring300, which may be implemented as a ferrite frame300surrounding the top/Q coil103of PTx device102. As a result, friendly metal of the PRx device104is effectively shielded from flux induced by coil103. Similarly, accessory904may include a ferrite frame covering all or substantially all of the transmitting area of PTx device904. In such embodiments, additional ferrite bars910may be provided near particular coils as required to provide the requisite level of shielding/flux redirection. Optional tabs912in ferrite ring/frame300may also be used to similar effect.

The foregoing describes exemplary embodiments of accessories for wireless power transfer systems that provide for improved coupling between wireless power transmitter (PTx) and wireless power receiver (PRx) devices. Such systems may be used in a variety of applications but may be particularly advantageous when used in conjunction with electronic devices such as mobile computing devices (e.g., laptop computers, tablet computers, smart phones, and the like) and their accessories (e.g., wireless earphones, styluses and other input devices, etc.) when used in conjunction with wireless charging devices (e.g., charging mats, pads, stands, etc.) constructed in anticipation of being used with different devices. Although numerous specific features and various embodiments have been described, it is to be understood that, unless otherwise noted as being mutually exclusive, the various features and embodiments may be combined various permutations in a particular implementation. Thus, the various embodiments described above are provided by way of illustration only and should not be constructed to limit the scope of the disclosure. Various modifications and changes can be made to the principles and embodiments herein without departing from the scope of the disclosure and without departing from the scope of the claims.

The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).