Proximity Sensor Accuracy for Portable Devices

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Solution Overview

Problem

Light-based proximity sensors in portable electronic devices face challenges in accurately determining the proximity of a user's head, particularly with dark-haired individuals or when the sensor is smudged with grease, leading to difficulties in disabling the touch screen display effectively to conserve power and prevent inadvertent input.

Innovation Solution

Incorporating a proximity sensor with a light-emitting element and a light-receiving element coupled to a controller, which uses reflected light intensity and ambient light variation, along with an accelerometer to accurately determine the device's position relative to the user's head and deactivate the touch screen display accordingly, even in challenging conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a light-based proximity sensor is used to detect user's head proximity, then the touch screen display can be disabled to conserve power, but the sensor fails to accurately detect proximity when the user has dark colored hair or the sensor is smudged with grease

Engineering Contradiction:

Improvepower consumptionVSAvoidproximity detection accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

An acoustic echo sensor is introduced as an intermediary detection mechanism to complement the optical proximity sensor. The acoustic sensor detects the acoustic echo generated when the device is placed near the user's head, providing an alternative detection path that is not affected by optical interference from dark hair or sensor smudging. This mediator approach ensures reliable proximity detection under conditions where the primary optical sensor fails.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If the touch screen display is disabled to conserve power during proximity detection, then energy is saved, but inadvertent touch input may still occur if proximity is not accurately determined

Engineering Contradiction:

Improvepower consumptionVSAvoidproximity detection reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system implements feedback by continuously monitoring acoustic echo characteristics and comparing them against threshold values to determine proximity state. The acoustic sensor provides feedback about the acoustic environment, which is processed to reliably determine whether the device is near the user's head. This feedback mechanism ensures that the touch screen is disabled only when proximity is confidently determined, preventing both unnecessary power consumption and inadvertent input.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If the proximity sensor relies on reflected light intensity, then the system can determine proximity, but dark colored hair with low reflectivity or grease smudges on the sensor reduce detection accuracy

Engineering Contradiction:

Improveautomatic proximity detectionVSAvoidreflected light detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces the optical detection mechanism with an acoustic detection mechanism. Instead of relying on reflected light intensity that is affected by surface properties like hair color and sensor cleanliness, the system uses an acoustic echo sensor to detect proximity through sound wave reflection. This substitution eliminates the measurement precision problems associated with optical detection while maintaining automatic proximity detection functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution ensures accurate and power-efficient operation of the touch screen display by effectively distinguishing between the user's head proximity and non-proximity, preventing inadvertent input and conserving battery life, even with dark hair or sensor smudging issues.

Implementation Method 1

When the cellular telephone is adjacent to the user's head, the emitted light from the infrared light-emitting diode will be reflected from the user's head and detected by the light detector

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

along with an accelerometer to accurately determine the device's position relative to the user's head

Methodology Applied

Scientific EffectAccelerometer detection: Accelerometer

Data Source

PatentUS9423831B2Portable electronic device and method operating same

Publication Date: 2016.08.23 SHENZHEN FUTAIHONG PRECISION IND CO LTD

AI summary

A portable electronic device includes a touch screen display, a proximity sensor, an ambient light sensor, and a controller. The proximity sensor detects and outputs an intensity of the reflected light. The ambient light sensor detects and outputs a variation of an ambient light level of the portable electronic device. The controller deactivates the touch screen display when it is determined by the controller that the intensity of the reflected light is greater than a predetermined intensity, and determines whether the variation of the ambient light level is greater than a predetermined level when it is determined by the controller that the intensity of the reflected light is less than the predetermined intensity. The controller further deactivates the touch screen display when it is determined by the controller that the variation of the ambient light level is greater than the predetermined level.