Patent Application
20140092543
Near Field Communication (NFC) is a communications technique that uses the magnetic portion of the transmitted electromagnetic field. It is being incorporated in many portable devices as a form of very-short-distance communication. However, magnetic flux can be heavily absorbed by metal, and the induced eddy current in the metal reduces the signal strength even more. Many of the present varieties of very thin notebook computers are manufactured with a metal chassis and also with other metal parts which are largely planar in shape. This provides additional structural strength, which can reduce damage caused by the flexing of the chassis in everyday use. However, the metal chassis and other internal metal parts can create problems for the NFC wireless communications functions. NFC antennas for such communication are generally placed inside the chassis, since external antennas may be unsightly and are subject to physical damage. To avoid the signal attenuation problem caused by the metal, NFC antennas may be placed under a hole in the metal chassis (e.g., under the non-metal area created for the keyboard). But internal metal parts that require a certain level of structural strength may not be readily adaptable for cutting holes that are large enough for an NFC antenna.
Some embodiments of the invention may be better understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:
In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
References to “one embodiment”, “an embodiment”, “example embodiment”, “various embodiments”, etc., indicate that the embodiment(s) of the invention so described may include particular features, structures, or characteristics, but not every embodiment necessarily includes the particular features, structures, or characteristics. Further, some embodiments may have some, all, or none of the features described for other embodiments.
In the following description and claims, the terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” is used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” is used to indicate that two or more elements co-operate or interact with each other, but they may or may not have intervening physical or electrical components between them.
As used in the claims, unless otherwise specified the use of the ordinal adjectives “first”, “second”, “third”, etc., to describe a common element, merely indicate that different instances of like elements are being referred to, and are not intended to imply that the elements so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
Discussions herein utilizing terms such as, for example, “processing”, “computing”, “calculating”, “determining”, “establishing”, “analyzing”, “checking”, or the like, may refer to operation(s) and/or process(es) of a computer, a computing platform, a computing system, or other electronic computing device, that manipulate and/or transform data represented as physical (e.g., electronic) quantities within the computer's registers and/or memories into other data similarly represented as physical quantities within the computer's registers and/or memories or other information storage medium that may store instructions to perform operations and/or processes.
The term “wireless” may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that communicate data by using modulated electromagnetic radiation through a non-solid medium. A wireless device may comprise at least one antenna, at least one radio, at least one memory, and at least one processor, where the radio(s) transmits signals through the antenna that represent data and receives signals through the antenna that represent data, while the processor(s) may process the data to be transmitted and the data that has been received. The processor(s) may also process other data which is neither transmitted nor received.
As used within this document, the term “communicate” is intended to include transmitting and/or receiving. This may be particularly useful in claims when describing the organization of data that is being transmitted by one device and received by another, but only the functionality of one of those devices is required to infringe the claim. Similarly, the exchange of data between a network controller and a mobile device (both devices transmit and receive during the exchange) may be described as ‘communicating’, when only the functionality of one of those devices is being claimed.
Antenna 320 is shown as a multiple-loop antenna, although other configurations may be used instead. Two loops are shown for simplicity of illustration, but one, three, or more loops may also be used. Antenna 320 is shown to have a rectangular shape, but it may have any other feasible shape, such as but not limited to square, circle, oval, or a more complex shape. In a typical NFC antenna in a notebook computer, the plane of antenna 320 may be parallel to the plane of baseboard 310, and it may be spaced within 2 centimeters either above (as shown) or below the baseboard. When current is induced in the loops (shown by clockwise arrow 335), the magnetic field created by this current may induce eddy currents in the opposite direction (shown by the counter clockwise arrow 345) in the metal baseboard. In a solid baseboard, this eddy current could be high, and it could therefore create significant reduction in the signal emanating from the antenna as measured outside the device chassis.
The purpose of slots 315 is to disrupt this eddy current. The disruption can theoretically be maximized if the direction of each slot is perpendicular to the direction of the eddy current at each location of the slot. The straight slots in
Because the sharp corners of the rectangular antenna can result in a somewhat unpredictable transition in the flux created near those corners, it may not be feasible to exactly match the direction of the slots near the corners to the eddy currents in those areas. The pattern of
The slots in
The slotted patterns may be used in any situation in which a metal sheet is placed in close proximity to an NFC antenna. The example shown in
The horizontal location of the antenna with respect to the keyboard may be varied according to design choice, but the short range of NFC communications (a few centimeters) may dictate this choice. For example, if the antenna is placed beneath the center of a full size keyboard in a notebook computer, the device to be communicated with may need to be held slightly above the center of the keyboard to be within communications range. On the other hand, if the keyboard opening extends near an edge of the notebook computer, the antenna may be placed close to that edge, even if the location of the actual keys doesn't extend that far. This would allow another device to be placed next to that edge and be within communications range.
These same principles may be applied to other types of devices, such as tablet computers and smart phones, in which a planar metal piece may be placed in a position to potentially interfere with the magnetic flux emanating from the NFC antenna. Such devices may or may not have a conventional keyboard, in which case the opening in the chassis may be for something other than a keyboard.
Although the metal baseboard in the foregoing description may be metal throughout, the same principles may be applied to sheets that are only partial metal. For example, a composite sheet made by layering metal with non-metal may be used. In that embodiment, the slots may be placed only in the metal layer, while the non-metal layer may remain solid, thus retaining structural strength while still benefiting from the slots in the metal. The metal layer may be attached to the underlying non-metal layer through any feasible means, such as using an adhesive. In some embodiments, the metal layer may be deposited on the non-metal layer through masked deposition, full deposition followed by etching, or through other deposition techniques.
The foregoing description is intended to be illustrative and not limiting. Variations will occur to those of skill in the art. Those variations are intended to be included in the various embodiments of the invention, which are limited only by the scope of the following claims.
