Patent Application
20210367342
This disclosure describes an optimized near-field communication (NFC) antenna structure for reduced coupling between an NFC coil of the antenna structure and a wireless charging (WLC) coil of a computing device (e.g., a smartphone). In aspects, the optimized NFC antenna structure includes the WLC coil and the NFC coil, which at least partially overlaps the WLC coil. The NFC coil of the optimized structure may include two sections that partially overlap the WLC coil and meet, over the WLC coil, at an angle to reduce coupling between the WLC coil and the NFC coil. The NFC coil may be partially disposed over the WLC coil such that a magnetic field generated by the NFC coil is induced into the WLC coil through mutual induction or coupling between the respective coils. In aspects, a geometry, shape, or position of the NFC coil is optimized to reduce the coupling between the respective coils, which may prevent operation of the NFC coil from impairing or interfering with operation of the WLC coil.
This disclosure describes various aspects of an optimized NFC antenna structure for reduced coupling. In aspects, a computing device includes a housing that substantially defines a housing plane of the computing device, a first coil, and a second coil. The computing device also includes a battery positioned within the housing and circuitry coupled to the battery. The first coil is coupled to the circuitry and includes a first conductor having a first shape that is positioned substantially parallel to the housing plane and at least partially within the housing, the first shape forming a winding. The second coil is coupled to the circuitry and includes a second conductor forming a second shape that is positioned substantially parallel to the housing plane and at least partially within the housing. The second coil is usable to generate a magnetic field when subject to an electric current. The second coil at least partially overlaps the first coil. The second shape of the second coil has at least three sections that include a first section that does not overlap the first coil, a second section coupled to a first end of the first section of the second coil, with the second section extending over the first coil. A third section of the second coil is coupled to a second end of the first section of the second coil, with the third section extending over the first coil and being coupled to the second section of the second coil. In aspects, an angle between the second section and third section of the second coil is in a range of 80 degrees to 160 degrees. In aspects, an optimized NFC antenna structure includes the first coil, the second coil, and the dielectric assembly, which may be embodied in a computing device to enable near-field communication and wireless charging.
An optimized NFC antenna structure for reduced coupling is described with reference to the following drawings:
The same numbers are used throughout the drawings to reference like features and components.
An optimized near-field communication (NFC) antenna structure may include an NFC antenna for contactless communication and a wireless charging coil (WLC) for receiving power from and/or transmitting power to another device. In aspects, the optimized NFC antenna structure may be used by a computing device to communicate with another computing device over a short distance (e.g., a distance less than 4 centimeters (cm)) without contact. The computing device may provide a current to the NFC antenna to generate radiation that may be at least partially received by a receiving NFC antenna of another computing device. For example, a smartphone may transfer payment information to an electronic reader by sending an alternating current to an NFC antenna of the smartphone to generate magnetic fields. When the smartphone is positioned near the electronic reader, changes in the magnetic flux (e.g., associated with the generated magnetic fields) over time may induce a current into a receiving NFC antenna of the electronic reader through inductive coupling to transfer the payment information. Alternatively or additionally, the computing device may use the WLC to provide power to other devices, which may include peripheral devices or other computing devices. In some cases, the computing device may use the WLC coil to receive power from another device, such as a wireless charger.
To improve performance of contactless communications using NFC antennas or wireless power transfer using the WLC, some manufacturers include one or more dielectric sheets in an optimized NFC antenna structure to localize magnetic fields and reduce magnetic-field loss. These dielectric sheets may also act as an insulator to protect circuitry of the computing device. In some cases, a respective magnetic field of the NFC antenna and the WLC couples with the other antenna or coil, which may impair or prevent operation of contactless communication or wireless charging functions of the computing device. Thus, in aspects of optimized near-field communication (NFC) antenna structure, a geometry of the NFC antenna (e.g., NFC coil) may be configured to reduce coupling between the co-located coils of the optimized antenna structure to improve contactless communication or wireless charging performance of a computing device.
As shown at 100-1, the computing device 102-1 may include a housing 104 that at least partially covers (e.g., encloses, protects) an optimized NFC antenna structure 106 and substantially defines a housing plane 108 (e.g., an XY plane across a front surface (screen) or back surface of the computing device 102-1). In this example, the optimized NFC antenna structure 106 includes an NFC antenna 110 (e.g., an NFC coil) and a WLC 112 that are oriented substantially parallel to the housing plane 108 and may be respectively positioned to at least partially overlap one another. In aspects, the computing device 102-2 includes a battery (not shown) positioned within the housing 104 and circuitry (not shown) that couples various components of the computing device. For example, the circuitry can couple a transceiver of the computing device 102-2 to the NFC antenna 110 or couple the battery to the WLC 112 to enable wireless reception or transmission of power by the computing device.
Example implementation at 100-2 illustrates the computing device 102-1 positioned near a receiving computing device 102-2 and generating magnetic fields 114 when a current 116 is supplied to the NFC antenna 110. Changes in the magnetic flux over time, associated with these magnetic fields 114, may induce an electromotive force (EMF) into a receiving antenna 118 in accordance with Faraday's law of induction. This EMF may correspond to an induced current 120 associated with, for instance, encrypted information used to complete a contactless payment.
Some preceding NFC antennas (e.g., rectangular shaped coils), however, may generate magnetic fields 114 that excessively couple with a WLC co-located with the NFC antenna, which may impair or disrupt operation of a wireless charging circuit coupled to the WLC. For example, magnetic fields generated by NFC polling transmissions may prevent the wireless charging circuit coupled to the WLC from detecting another device or result in false detection of another source of wireless charging magnetic fields. In some cases, this can cause the wireless charging circuit to enter a timeout state or to cease detection operations. As a result, the user may be prevented from accessing wireless charging functionalities of a computing device when the NFC antenna is active for various polling or communication operations. Consequently, barriers may exist that prevent users from efficiently using contactless communication and wireless charging functionalities of a computing device. This disclosure describes an optimized NFC antenna structure that utilizes various geometries and arrangements of an NFC antenna (NFC coil), a WLC, and dielectric assembly to reduce coupling of a magnetic field between the NFC antenna and the WLC. By so doing, a computing device may operate an NFC transceiver with less or minimal interference to wireless charging circuitry of the computing device.
In general, an NFC antenna 110 or WLC 112 may refer to an electromagnetic coil comprising a conductive material (e.g., copper wire or copper traces) that enables the flow of current at a resonant frequency, for instance, of 13.56 Megahertz (13.56 MHz) for NFC or 150 kilohertz (150 kHz) for wireless charging. In aspects, the WLC 112 may be implemented generally as a conductive coil (e.g., wires or traces) with an appropriate resonance for wireless charging operations, which may include transmitting wireless power to another device or receiving wireless power from a power source. In aspects, the WLC 112 may be implemented as any suitable shape, which may include a circle, an ellipse, a rectangle, a rectangle with rounded corners, a square with rounded corners, a stadium, a polygon with rounded corners, or the like.
The electrical characteristics of the NFC antenna may include an inductance, a resistance, and a capacitance based on an associated topography (e.g., dimensions, number of windings, spacing). For example, some NFC antennas are configured for an inductance of 200-600 nanohenry (nH) with a quality factor of approximately 8-15 and a self-resonant frequency greater than 30 MHz. NFC antennas may be used to read and/or write information on NFC tags, communicate with another NFC antenna of a second device, and/or perform card emulation for transactions including payments or ticketing.
As shown in
In aspects of an optimized NFC antenna, conductors (e.g., coils, wires, traces) of the NFC antenna 110 may be formed in substantially non-circular shapes, which include polygons with at least three sections with angular or rounded corners (shown in relation to the housing plane 108). In some cases, the NFC antenna 110 is formed into a triangle shape or trapezoid shape with one or more sections that do not extend across the WLC 112 in an orthogonal fashion. In this example, the NFC antenna 110 includes a first section 208 that does not overlap the WLC 112 and is positioned over the second section of dielectric material 206 (e.g., ferrite layer). The NFC antenna 110 also includes a second section 210 and a third section 212 that extend at least partially over the WLC 112 with an angle between the second and third sections being in a range of 80 degrees to 160 degrees. The second section 210 and/or third section 212 may be positioned at least partially over a center, core, cavity, or internal diameter (e.g., a space or volume between windings) of the WLC 112. In some implementations, the angle between the second section 210 and the third section 212 is within a range of 130 degrees to 140 degrees. In aspects, the NFC antenna 110 may include a fourth section 214 that couples the third section 212 to the first section 208 (or any intermediate section) of the NFC antenna. The fourth section of the NFC antenna 110 may at least partially overlap the WLC 112 or be positioned such that the fourth section 214 does not overlap the WLC 112. As such, the NFC antenna 110 may be formed or configured generally in a trapezoid shape or isosceles trapezoid shape that partially overlaps the WLC 112. This is but one configuration of an optimized NFC antenna structure, which is further described along with other example configurations throughout this disclosure.
In the example view 304-1, a portion of the NFC antenna 110 (e.g., a first section) may be positioned over or overlap the first section of dielectric material 204 and the second section of dielectric material 206. Here, note that this portion of the NFC antenna 110 and/or the second section of dielectric material 206 is not positioned over or overlap the WLC 112. With reference to view 304-2, the WLC 112 is positioned over the first section of dielectric material 204 (e.g., NC sheet), which is shown in reference to the substrate 202 (e.g., device main logic board or ground plane). The NFC antenna 110 is positioned to partially overlap the WLC 112 and the second section of dielectric material 206 (e.g., ferrite layer). In some cases, the illustrated configuration of the NFC antenna 110 and WLC 112 provide a compact and space-efficient implementation that enables contactless communication and/or wireless charging functionalities.
In the example view 404-1, the NFC antenna 110 and a portion of the first section of dielectric material 204 (e.g., NC sheet) may be positioned near or in contact with the housing 402. For example, one or more components of the optimized NFC antenna structure 106 may be assembled in relation to the housing 402 or the substrate 202 using various adhesives or fabrication techniques. In other words, the components of the optimized NFC antenna structure 106 may be assembled as a sub-assembly of coils and dielectric material (e.g., flexible circuits and dielectric layers), which is then assembled between the substrate 202 and the housing 402 (e.g., positioned or adhered to the housing or substrate).
With reference to view 404-2, the WLC 112 is also positioned near or against the housing 402 and below a portion of the NFC antenna 110. Here, note that a first portion of the WLC 112 is co-planar with the NFC antenna 110 and a second portion of the WLC 112 is positioned below a portion of the NFC antenna 110. As shown at 402-2, a contour of the first section of dielectric material 204 (e.g., NC sheet) may follow a general contour of components positioned above the first section, which include the NFC antenna, WLC 112, and the second section of dielectric material 206 (e.g., ferrite layer). As noted, the example configurations described herein may enable a compact and space-efficient implementation of the NFC antenna 110 and the WLC 112 in a device with reduced coupling.
As shown at 500, the NFC antenna 110 can be configured with a second section 210 and a third section 212 that have an interior angle 502 (e.g., angle between the sections) that is within a range of 80 degrees to 160 degrees. In some cases, the NFC antenna 110 is configured such that an interior angle 504 between the second section 210 and the fourth section 214 is within a range of 85 degrees to 95 degrees. In this example, the NFC antenna 110 is implemented such that an interior angle between the second section 210 and the third section 212 is approximately 135 degrees. Alternatively, angular dimensions of the NFC antenna sections may be defined as an exterior angle 506 with reference to the third section 212 or an orthogonal line 508 across the WLC 112. Thus, in some cases, an exterior angle of the third section 212 and one of the second section 210 or fourth section 214 is in a range of ten degrees to 50 degrees. As shown in
In aspects, the NFC antenna 110 can be configured such that an interior angle 810 between the second section 804 and the third section 806 (e.g., angle between the sections) is within a range of 80 degrees to 160 degrees. In some aspects, the angle between the second section 804 and the third section 806 of the NFC antenna 110 is within a range of 125 degrees to 145 degrees. In this example, the NFC antenna 110 is implemented such that an interior angle between the second section 804 and the third section 806 is approximately 135 degrees. Alternatively, angular dimensions of the NFC antenna sections may be defined as an exterior angle 812 with reference to the third section 806 or an orthogonal line 814 across the WLC 112. Thus, in some cases, an exterior angle of the second section 804 and the third section 806 is in a range of ten degrees to 50 degrees. As shown in
Although an optimized antenna structure for reduced coupling has been described in language specific to features, it is to be understood that the subject of the appended claims is not necessarily limited to the specific techniques described herein. Rather, the specific techniques are disclosed as example implementations of an optimized antenna structure for reduced coupling between coils or antennas (e.g., an NFC coil and a WLC coil).
This application claims priority to U.S. Provisional Patent Application Ser. No. 63/230,396 filed on Aug. 6, 2021, the disclosures of which are incorporated by reference herein in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 63230396 | Aug 2021 | US |
