Integrated Antenna Proximity Sensing for PCB Space and SAR Control
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Solution Overview
Problem
Capacitive proximity sensors in electronic devices occupy significant space on printed circuit boards due to the separate sensing elements and antennas, leading to increased device volume and inefficiencies in power adjustment based on object proximity.
Innovation Solution
A combination sensing element and antenna that functions both as a sensing element and antenna, integrated with a filter circuit to reduce noise and adjust transmission power based on capacitance changes, eliminating the need for additional components and reducing PCB volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate sensing element is used in capacitive proximity sensors, then detection function is achieved, but PCB area occupied increases leading to larger device volume
Solution Approach 1:
The patent combines the sensing element and antenna into a single integrated structure. The sensing element is formed as a conductive pattern on the PCB that simultaneously serves as both the capacitive sensing element for proximity detection and as an antenna for wireless communication, eliminating the need for separate components and reducing PCB area occupation.
Solution Approach 2:
The conductive pattern on the PCB performs multiple functions: it acts as the sensing element for capacitive proximity sensing, serves as an antenna for RF communication, and provides grounding function. This multi-functionality reduces the number of components needed and minimizes the overall PCB area required.
2Reliability
If transmit power is increased to meet SAR limits when no object is present, then radiation transmission levels are sufficient, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts the transmit power of the antenna based on real-time proximity detection feedback. When an object is detected near the device, the transmit power is reduced to meet SAR limits. When no object is present, the transmit power is increased to ensure sufficient communication range, optimizing energy consumption based on actual environmental conditions.
Solution Approach 2:
The capacitive proximity sensor provides continuous feedback about the presence and distance of objects near the device. This feedback is used by the control system to dynamically adjust the antenna transmit power, creating a closed-loop system that optimizes both SAR compliance and energy efficiency based on real-time conditions.
3Reliability
If additional components are added for sensing and power adjustment, then detection and power control functions are improved, but device complexity increases
Solution Approach 1:
The sensing element and antenna are merged into a single conductive structure on the PCB, eliminating the need for separate sensing components and external antennas. This integration reduces component count while maintaining both proximity detection and wireless communication functions.
Solution Approach 2:
The integrated conductive pattern performs multiple functions including proximity sensing, antenna operation, and grounding, reducing the need for additional dedicated components and simplifying the overall device architecture while maintaining full functionality.
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 detection of external objects and adaptive power adjustment without increasing the device's volume, enhancing radiation efficiency and meeting regulatory SAR limits while minimizing additional components.
Implementation Method 1
Capacitance of the sensing element changes according to the presence or absence of the conductive or the dielectric object in the vicinity of the sensing element
Data Source
AI summary
A proximity sensor module used in an electronic device includes a combination sensing element and antenna, and a detecting circuit electrically connected to the combination sensing element and antenna. The combination sensing element and antenna is used to detect whether an external object is in vicinity of the combination sensing element and antenna according to capacitance changes of the combination sensing element and antenna in presence or absence of an external object in the vicinity, the detecting circuit detects the capacitance changes, and generates a signal associated with the changes to decrease or increase transmission power transmitted to the combination sensing element and antenna.