Proximity Sensing for Automatic Audio Gain Switching in Mobile Phones
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Solution Overview
Problem
Current portable electronic devices face issues with sound pressure levels when users switch between holding devices close to their ears or away, leading to potentially damaging volumes, and microphone signal quality is affected by varying distances from the user's mouth.
Innovation Solution
Incorporating a sensor to detect proximity to a human body part, allowing a control circuit to adjust the gain of audio interfaces (speakers and microphones) automatically, enabling operation in 'close talk' and 'far talk' modes without manual volume adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual volume control is used, then users can adjust gain for different modes, but users may experience high sound pressure levels damaging their ears when holding device close
Solution Approach 1:
The system automatically detects proximity to the user's ear and adjusts the speaker gain accordingly without requiring manual user input. The proximity sensor and control circuit work together to self-regulate the audio output based on detected conditions
Solution Approach 2:
The proximity sensor provides continuous feedback about the device's distance from the user's ear to the control circuit, which then adjusts the speaker gain in real-time based on this feedback signal
2Object-affected harmful factors
If dual speaker system is used, then sound pressure levels can be optimized for different modes, but device complexity increases
Solution Approach 1:
Instead of adding hardware components, the system changes the operational parameters (gain levels) of the existing single speaker based on proximity detection. This achieves mode-specific optimization without increasing device complexity
3Measurement precision
If AGC is used for microphone, then signal quality is maintained at varying distances, but gain adjustment may not respond to proximity changes
Solution Approach 1:
The proximity sensor provides direct feedback about device-to-mouth distance to the control circuit, which then adjusts microphone gain specifically in response to proximity changes, complementing the AGC functionality
Data Source
AI summary
A portable electronic device that automatically detects its mode of use and alters a characteristic of its user interface to match the mode of use. A mobile telephone is described as an example of a portable electronic device. The telephone is equipped with a proximity sensor that may indicate whether the telephone is held close or far from the user's face. Based on the proximity to the user's face, gains in the audio interface are adjusted. The gain is reduced when the device is held close to a user's face and increased when the device is moved away from the user's face. This approach is well suited for use in connection with portable devices that use voice command interfaces.