Shared Coil Antenna for NFC and Proximity Sensing
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Solution Overview
Problem
In thin portable devices, the limited space poses a challenge for efficiently integrating near field communication (NFC) and proximity sensor functions, often requiring significant space and compromising their performance due to competing demands for antenna space within a metallic chassis.
Innovation Solution
Integrating a proximity sensor with an NFC module to use a single coil antenna for both proximity sensing and NFC operations, configuring the coil antenna to switch between open and closed spiral shapes for low-frequency proximity sensing and high-frequency NFC functions, respectively, and employing passive or active devices to isolate these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate antennas are used for NFC and proximity sensor, then each function can operate independently, but the device requires more space and becomes harder to fit in thin portable devices
Solution Approach 1:
The patent combines the NFC antenna and proximity sensor antenna into a single shared coil antenna structure. The same physical antenna is used for both NFC communication at 13.56 MHz and proximity sensing at lower frequencies, eliminating the need for separate antenna spaces while maintaining both functions through frequency-based signal separation.
Solution Approach 2:
The single coil antenna is designed to serve multiple functions: it acts as both the NFC antenna for contactless communication and the proximity sensor antenna for detecting nearby objects. This multi-functional design allows one component to replace what would traditionally require two separate components, saving valuable space in thin portable devices.
2Area of stationary object
If antenna size is reduced to fit thin devices, then space constraints are met, but the performance of NFC and proximity sensor is compromised
Solution Approach 1:
The patent uses parameter changes in the form of frequency separation to maintain performance with a smaller antenna. By operating NFC at 13.56 MHz and proximity sensing at lower frequencies (e.g., 125 kHz or 134.2 kHz), the system can distinguish between the two functions using the same physical antenna, allowing the antenna to be smaller while still maintaining adequate performance for both functions.
Solution Approach 2:
The patent introduces signal processing circuits and frequency separation mechanisms as intermediaries to manage the shared antenna. These intermediaries process the signals from the single antenna to distinguish between NFC communications and proximity sensing, allowing the reduced-size antenna to maintain performance through intelligent signal management rather than relying on physical size alone.
3Shape
If metallic chassis is used for aesthetic reasons, then device appearance is improved, but NFC and proximity sensor signals are interfered with
Solution Approach 1:
The patent uses filtering circuits and signal processing intermediaries to isolate the NFC and proximity sensor signals from interference caused by the metallic chassis. These intermediaries selectively pass the desired frequency ranges while blocking interfering signals, allowing the metallic chassis to be used for aesthetic purposes without compromising the electromagnetic signal integrity of the shared antenna system.
Solution Approach 2:
The patent applies local quality improvements by positioning the shared antenna and its associated circuitry in specific locations within the device where interference from the metallic chassis is minimized. By carefully selecting the antenna placement and using localized shielding or grounding techniques in critical areas, the system maintains signal quality while preserving the overall metallic chassis design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for efficient operation of both NFC and proximity sensing functions in thin portable devices, complying with SAR regulations and reducing power consumption by optimizing antenna configuration and signal separation.
Implementation Method 1
The radiator radiates the signal to produce an electromagnetic field near the radiator. The electromagnetic field changes by a predetermined amount responsive to the proximity of the radiator to a predetermined object, such as a human body, external to the wireless communication device.
Implementation Method 2
Near field coupling functions use radio frequency (RF) antennas in each of the devices to transmit and receive electromagnetic signals.
Data Source
Figure 1(A)~1(B)
Figure 2
Figure 3
AI summary
Described herein are techniques related to near field coupling and proximity sensing operations. For example, a proximity sensor uses a coil antenna that is utilized for near field communications (NFC) functions. The proximity sensor may be integrated into an NFC module to form a single module.