Portable Media Speaker Power Control by Battery-Based SPL Limiting
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Solution Overview
Problem
Portable media players face challenges in managing power consumption when connected to large speaker systems, as the power requirements for driving the speakers exceed the device's capabilities, limiting the listening experience for multiple users and reducing battery life.
Innovation Solution
A method is implemented to manage power in a media delivery system by setting a maximum allowable sound pressure level for speakers based on the available charge, reducing the sound pressure level when power is low to conserve energy, and providing user feedback before shutting down the device to avoid audio artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the portable media player is connected to a media delivery accessory unit with large speakers, then the listening experience for multiple users is improved, but the power consumption exceeds the device's capabilities
Solution Approach 1:
The system dynamically adjusts the maximum allowable sound pressure level (SPL) based on the operating mode (DC or AC). In DC mode, the maximum SPL is set to a lower DC maximum allowable SPL, while in AC mode, a higher maximum SPL is permitted. This dynamic adaptation allows the system to optimize performance based on available power sources.
2Illumination intensity
If the maximum sound pressure level is increased to provide better audio output, then the listening quality is improved, but the battery life is reduced
Solution Approach 1:
The system changes the operating parameter (maximum allowable SPL) based on the power source available. When operating on DC power (battery), the maximum SPL is reduced to conserve energy. When AC power is available, the maximum SPL is increased to provide better audio output. This parameter adjustment resolves the contradiction between audio quality and battery life.
3Loss of energy
If the device shuts down abruptly to conserve power, then the power consumption is reduced, but audio artifacts are generated
Solution Approach 1:
The system provides user feedback indicating that power loss is imminent before actually shutting down. This preliminary warning allows the system to prepare for shutdown in a controlled manner, preventing abrupt termination that would cause audio artifacts. The feedback is continued until all residual power is exhausted, ensuring a smooth transition.
Data Source
AI summary
A consumer electronic product (e.g., a portable media player ported to a media delivery accessory) is powered by a limited capacity DC power source (such as a battery or mini-fuel cell). The consumer electronic product limits the maximum allowable sound pressure level (SPL) that can be produced by the speakers. In one embodiment, the maximum allowable SPL is based upon an amount of stored energy available in the limited capacity DC power source.