Mobile Proximity Sensor Compensation for Accurate RF Power Control

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Solution Overview

Problem

Mobile devices face challenges in accurately detecting proximity to the human body, leading to potential health risks from excessive RF radiation and connectivity issues due to inaccurate proximity sensor readings, which fail to adjust RF power output effectively.

Innovation Solution

A method involving a proximity sensor with a capacitive touch controller that determines a compensation value and compares it to a reference value to validate proximity, adjusting RF power output to comply with safety regulations and maintain connectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If proximity sensor readings are used to control RF power output, then health safety from RF radiation is improved, but measurement precision of proximity detection deteriorates due to environmental capacitance interference

Engineering Contradiction:
ImproveRF radiation exposureVSAvoidproximity detection accuracy
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

A compensation capacitor is introduced as an intermediary element to counteract the environmental capacitance interference. The compensation capacitor has a capacitance value equal to the environmental capacitance, and is connected in parallel with the proximity sensor to cancel out the interfering capacitance effects, thereby improving measurement precision without compromising RF radiation safety control

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically adjusts the compensation capacitor value based on detected environmental capacitance changes. By monitoring the environmental capacitance and modifying the compensation capacitor's capacitance accordingly, the system maintains accurate proximity detection across varying environmental conditions while ensuring proper RF power control for health safety

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If proximity sensor accuracy is improved through environmental capacitance compensation, then proximity detection precision is improved, but device complexity increases

Engineering Contradiction:
Improveproximity detection accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The compensation capacitor is integrated into the existing proximity sensor circuitry rather than being implemented as a separate system. The capacitor is connected in parallel with the sensor element and controlled through the same control logic that manages RF power output, merging multiple functions into a unified system that reduces overall device complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system automatically detects environmental capacitance changes and self-adjusts the compensation capacitor value without requiring manual calibration or external intervention. The control logic monitors sensor readings and dynamically modifies compensation parameters, enabling the system to maintain high detection accuracy while minimizing user burden and system complexity

Inventive Principle:
Principle #25Self-service

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 approach enhances the accuracy of proximity detection, reducing RF radiation exposure and ensuring compliance with safety limits while maintaining device connectivity.

Implementation Method 1

A method and device are provided for improved accuracy of proximity and touch detection in mobile devices

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP4117183A1Method and device for improved accuracy of proximity and touch detection in mobile devices
Publication Date: 2023.01.11 SEMTECH CORP
  • EP4117183A1 patent drawingFigure 1a~1b
  • EP4117183A1 patent drawingFigure 1c~2c
  • EP4117183A1 patent drawingFigure 3a~3b

AI summary

A mobile device has a proximity sensor. A compensation value of the proximity sensor is determined. The compensation value is compared to a reference compensation value to determine validity of the compensation value. A capacitance of the proximity sensor is measured. A value of the capacitance of the proximity sensor is adjusted based on the compensation value. A coefficient defining a relationship between a capacitance of the proximity sensor and a temperature of the mobile device is calculated. A temperature sensor is coupled to the proximity sensor. The temperature of the mobile device is measured. A value of the capacitance of the proximity sensor is adjusted based on the coefficient and the temperature of the mobile device. The adjusted capacitance value is compared to a threshold capacitance value to determine proximity of an object to the mobile device. A radio frequency signal is adjusted by detecting proximity.