The invention relates to mobile communication generally and, more particularly, to a method and/or apparatus for implementing an indium tin oxide loop antenna for near field communication.
Conventional mobile devices can include an antenna for near field communication (NFC) such as USB links. A conventional NFC antenna consists of a coil of copper wire or a flat conductive coil trace pattern formed on either a top or bottom surface of a substrate. Care must be taken in the placement of the NFC antenna on the top or bottom surfaces to avoid interference with displays and other structures such as touchscreen conductors. In some conventional devices, the NFC antenna is located on a separate printed circuit board (PCB) substrate. The addition of a separate printed circuit board substrate increases manufacturing and bill of material (BOM) costs, as well as increases the weight of the mobile device.
It would be desirable to have an indium tin oxide loop antenna for near field communication that reduces placement and BOM cost considerations.
The invention concerns an apparatus including a display and a transceiver. The display has a lateral surface. The lateral surface has disposed thereon a line comprising a thin-film conductive material. The line is patterned to form one or more loops around the display. The transceiver is electrically connected to the line. The line forms a radiating structure during a radio frequency (RF) operation.
Embodiments of the invention will be apparent from the following detailed description and the appended claims and drawings in which:
Embodiments of the invention include providing a thin-film (e.g., indium tin oxide (ITO), etc.) loop antenna for near field communication (NFC) that may (i) reduce a bill of materials (BOM) for a radio frequency device, (ii) reduce cost, (iii) reduce weight, and/or (iv) locate a near field communication loop antenna on a lateral surface of a liquid crystal display (LCD).
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The top surface of the display 100 may comprise a flexible optical grade plastic (e.g., polyethylene terephthalate (PET), polyester, etc.) or a stable substantially rigid transparent material (e.g., glass, acrylic, etc.). The display 100 generally includes a lower layer or layers implementing the display (e.g., LCD, LED, TFT, etc.). The layers of the display 100 are generally held together and sealed with a gasket adhesive, which isolates the display and/or touchscreen from the external environment. The display 100 has a lateral surface 106. The lateral surface 106 is generally perpendicular to the top surface of the display 100 and comprises four connected regions which are generally referred to as sides of the display 100.
The sides of the display 100 may comprise plastic or glass areas on which a circuit layer comprising a thin-film conducting material (e.g., indium tin oxide (ITO), indium zinc oxide (IZO), etc.) is deposited and patterned to form a line 110 having one or more loops. The line and loop(s) 110 may be configured (e.g., length and thickness adjusted) to form a radiating (antenna) structure appropriate for RF operation (e.g., transmitting, receiving, performing near field communication, etc.). For example, the line and loop(s) 110 may be sized, in some embodiments, for operation at a frequency of about 13.6 MHz. The line and loop(s) 110 may be sized for forming a radiating structure for other (e.g., higher, lower, etc.) frequencies as well. For example, the skin effect at 2.5 and 5.2 GHz keeps most of the electrons in the outer surface of the thin-film conducting material, so the fact that the line and loop(s) 110 comprise a thin wire is generally not an issue. Although the radiation resistance and dissipation resistance may be higher than for a very thick copper line, the higher radiation resistance and dissipation resistance may be compensated for with a transceiver matching circuit. In comparison, conventional antennas are typically electrically small and have less than desirable directivity (e.g., 1.2 to 1.8 dBi). In addition, because the line and loop(s) 110 are located outside the visible (viewing) region 102 of the display 100, a thicker layer of the thin-film conducting material may be used to reduce the resistance.
The thin-film conducting material may be deposited (e.g., sputtered, etc.) on the lateral surface 106 of the display 100. The thin-film conducting material may be patterned (e.g., etched) to form the line and loop(s) 110, as well as connecting pads 112 and 114. In one example, an insulating layer may be deposited to allow connection of the pad 112 to an upper end of the line and loop(s) 110.
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In some embodiments, a flexible strip 210 with one or more line segments 212 may be attached (e.g., bonded, glued, adhered, etc.) to the lateral surface 206 of the display 200. The line segments 212 may comprise a thin-film conducting material (e.g., ITO, IZO, etc.). The line segments 212 may be connected together at a point where ends of the strip 210 meet to form a continuous loop antenna. The loop antenna formed by the line segments 212 may be connected to RF circuitry via a contact 214 and a contact 216. In one example, the contacts 214 and 216 may be formed at the junction of the ends of the strip 210. The contact 214 may be connected to an upper end of the loop antenna and the contact 216 may be connected to a lower end of the loop antenna.
The thin-film conducting material forming the line segments 212 may be deposited (e.g., sputtered, etc.) on the flexible strip 210. The flexible strip 210 may comprise a flexible material (or substrate) such as polyethylene terephthalate (PET), polyester, etc. The thin-film conducting material may be patterned (e.g., etched) to form the line(s) 212, as well as pads for the contacts 214 and 216.
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In some embodiments, a device comprising a display may be implemented with a thin-film (e.g., ITO, IZO, etc.) loop antenna disposed around a lateral surface of the display. Disposing the antenna around the lateral surface of the display avoids interference with viewing of the display, as well as interconnections that may also be located in the periphery of the top surface of the display (e.g., for supporting connection to an electro grid used as a touchscreen). In general, the ITO loop antenna may be formed as one or more loops of material traversing around the lateral surface of the display. The ITO loop may be formed with a thickness providing a low resistance and, therefore, better antenna characteristics since the lateral surface of the display is not used for transmitting an image as is the top surface. In alternative embodiments, the technique of using the lateral surface of the display as the location for the near field communication antenna may also support the placement of other types of antennae (e.g., whip, monopole, di-pole, etc.), which could be placed along less than all four sides of the display.
Although the examples described above refer to indium tin oxide (ITO) and/or indium zinc oxide (IZO), it will be apparent to those of ordinary skill in the art that the thin-film conductive (or conducting) material used to form the loop(s) 110 and lines 212 may include, for example, (i) conductive polymers (e.g., including polypyrrole, polyaniline or polythiophene), (ii) transparent conducting oxides (e.g., including tin doped indium oxide (ITO), fluorine doped zinc oxide (FZO), aluminum doped zinc oxide AlZO, indium doped zinc oxide (IZO), antimony doped tin oxide (SbTO), and fluorine doped tin oxide (FTO)), and (iii) low-resistance metallic material such as molybdenum (Mo), silver (Ag), titanium (Ti), copper (Cu), aluminum (Al), and/or molybdenum/aluminum/molybdenum (Mo/Al/Mo). The terms “may” and “generally” when used herein in conjunction with “is(are)” and verbs are meant to communicate the intention that the description is exemplary and believed to be broad enough to encompass both the specific examples presented in the disclosure as well as alternative examples that could be derived based on the disclosure. The terms “may” and “generally” as used herein should not be construed to necessarily imply the desirability or possibility of omitting a corresponding element.
While the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the scope of the invention.
Number | Date | Country | |
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61763183 | Feb 2013 | US |