Handheld Loudspeaker Directional Audio Control
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Solution Overview
Problem
Handheld device loudspeakers lack control over the number of people who can overhear conversations, with existing systems either emitting sound over a large solid angle, potentially facilitating eavesdropping or not directing sound effectively for personal use.
Innovation Solution
A directional loudspeaker system for handheld devices that uses a combination of dipole and monopole loudspeakers, with signal filtering to achieve constructive and destructive interference patterns, allowing for controlled sound radiation towards the user while minimizing sound reaching others.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a loudspeaker emits sound over a large solid angle, then more people can hear the conversation, but privacy is compromised and eavesdropping becomes easier
Solution Approach 1:
The patent applies local quality by creating different sound radiation characteristics in different spatial directions. The loudspeaker system generates a sound field with enhanced intensity in specific directions (toward the user) and reduced intensity in other directions (away from the user), thereby providing good sound distribution for the user while minimizing eavesdropping risk in surrounding areas.
Solution Approach 2:
The patent employs asymmetry by producing an asymmetric sound radiation pattern instead of uniform omnidirectional emission. The sound field is deliberately shaped to be stronger in certain directions and weaker in others, creating a directional audio output that favors the user's position while reducing sound exposure to others, thus resolving the contradiction between sound distribution and privacy protection.
2Object-affected harmful factors
If a loudspeaker directs sound in a specific direction, then privacy is improved, but sound quality and coverage for multiple users deteriorates
Solution Approach 1:
The patent applies dynamics by making the sound radiation pattern adjustable rather than fixed. The system can dynamically alter the directionality and spatial distribution of sound based on operational requirements, allowing it to switch between more directional modes (for privacy) and more omnidirectional modes (for coverage), thereby resolving the contradiction between privacy protection and sound coverage.
3Device complexity
If conventional loudspeakers are used, then device complexity is low, but control over sound radiation patterns is insufficient
Solution Approach 1:
The patent applies universality by designing a loudspeaker system that performs multiple functions: it can operate in omnidirectional mode for general use and switch to directional modes for privacy-sensitive applications. This multi-functionality allows a single system to adapt to different usage scenarios, providing both simplicity and advanced sound radiation control without requiring multiple separate devices.
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 system effectively directs sound towards the user while reducing sound exposure to others, enhancing privacy and sound quality by using phase shifting and filtering to steer sound radiation patterns.
Implementation Method 1
A directional loudspeaker system for handheld devices that uses a combination of dipole and monopole loudspeakers, with signal filtering to achieve constructive and destructive interference patterns
Data Source
AI summary
Loudspeaker systems for handheld devices (2400, 2500) such as cellular telephones (100, 1400, 1600, 1900) are provided. The loudspeaker systems include at least one omnidirectional monopole loudspeaker (404, 1504, 1802, 1918, 1920) and at least one dipole loudspeaker (402, 1502, 1804, 1914, 1916). Filtering is used to compensate for differences between electric-to-acoustic signal transfer functions of the loudspeakers in order to achieve destructive interference of emitted audio in one direction and reinforcement in another direction. Various loudspeaker systems that are reconfigurable from directional mode, to omnidirectional mode are provided. Filtering is also used to add a frequency dependent phase to one signal in order to alter a direction of maximum sound pressure level. Two monopole-dipole pairs can be used to produce a stereo effect. The monopole and dipole loudspeakers can be housed in a detachable loudspeaker accessory (200).