Touchpad Proximity Sensing for Tablet-Mode SAR Control
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Solution Overview
Problem
Information handling systems face challenges in detecting human proximity to antennas due to interference from metallic chassis, which affects Specific Absorption Rate (SAR) regulation compliance, especially in tablet configurations where traditional proximity sensors' effectiveness is reduced.
Innovation Solution
Repurposing the touchpad as a proximity sensor by operatively coupling its metallic layers to an integrated sensor hub or proximity sensor IC, allowing it to detect human presence and adjust antenna power accordingly, even when the system is in a tablet configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional proximity sensors are used to detect human proximity to antennas, then SAR regulation compliance can be achieved, but the metallic chassis interferes with detection accuracy and effectiveness is reduced in tablet configurations
Solution Approach 1:
The touchpad is repurposed to serve dual functions: its original input function and a new proximity sensing function. The metallic layers of the touchpad are operatively coupled to the integrated sensor hub, allowing the same component to perform both user input and human proximity detection, eliminating the need for separate proximity sensors that would be interfered with by the metallic chassis
Solution Approach 2:
The integrated sensor hub acts as an intermediary that processes signals from the touchpad's metallic layers to detect human proximity. This intermediary component enables the touchpad to function as a proximity sensor by mediating between the touchpad's capacitive changes and the system's SAR control mechanisms
2Measurement precision
If additional proximity sensors are added to improve detection accuracy, then measurement precision improves, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of adding separate proximity sensors, the invention reuses the existing touchpad structure for dual purposes. The metallic layers already present in the touchpad are repurposed as sensing elements, eliminating the need for additional sensor components and reducing overall device complexity
Solution Approach 2:
The touchpad's own metallic layers are used to detect proximity, meaning the existing structure serves its original function while simultaneously providing the sensing capability. This self-service approach eliminates the need for separate sensing components
3Measurement precision
If the touchpad is repurposed as a proximity sensor, then proximity detection range and accuracy are enhanced, but the touchpad's input functionality may be affected
Solution Approach 1:
The system dynamically switches the touchpad's operational mode based on context. The controller can configure the metallic layers for either input detection or proximity sensing as needed, allowing the touchpad to adapt its function rather than being fixed in one mode. This dynamic reconfiguration resolves the conflict between maintaining input functionality and achieving accurate proximity detection
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
Enhances the range and accuracy of proximity detection, ensuring SAR levels are maintained within safety thresholds while maintaining data throughput and aesthetics by integrating the touchpad's functionality into the system's safety mechanisms.
Implementation Method 1
the touchpad to detect changes in capacitance
Data Source
AI summary
An information handling system may include a processor, a memory, a radio to transceive wirelessly via an antenna with a wireless network, and a touchpad to receive touch input via a surface of the touchpad when the information handling system is detected in a clamshell configuration, where the touch input is received by a touchpad driver and processed to a corresponding touch input command. An orientation sensor to detect when the information handling system is changed to a tablet configuration and a controller to deactivate the touchpad to receive the touch input for processing to a corresponding touch input command and to activate and operatively couple a metallic layer of the touchpad to a proximity sensor integrated circuit to detect when a user's body is close to the antenna to reduce the power for transmission via the antenna to reduce a specific absorption rate (SAR) level.