Electric Rocking Mode Damper for Micro Speakers
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Solution Overview
Problem
Existing micro speakers in mobile devices face issues with membrane tumbling due to asymmetry, leading to reduced sound pressure output and potential damage, which current damping materials cannot effectively address across various environmental conditions.
Innovation Solution
The use of two figure-8 shaped detection coils to detect membrane tumbling along perpendicular axes, with a damping coil to electrically damp the movement, eliminating the need for additional damping material and making damping independent of environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If damping membrane material is used to prevent membrane tumbling, then membrane stability is improved, but damping efficiency strongly depends on environmental conditions
Solution Approach 1:
The patent replaces the mechanical damping system (damping membrane material) with an electrical damping system. A sensor coil detects membrane tumbling by measuring changes in magnetic flux, and a damping coil generates electromagnetic forces to counteract the tumbling. This electrical system eliminates dependence on environmental conditions that affect material properties, while maintaining effective membrane stabilization.
2Device complexity
If a single coil sensor is used to detect tumbling, then the sensor structure is simple, but the induced voltage from tumbling cannot be detected due to cancellation
Solution Approach 1:
The patent divides the sensor into two separate coils positioned at different locations relative to the magnet system. Each coil independently measures magnetic flux changes, and their signals are combined to detect tumbling. This segmentation prevents signal cancellation while maintaining relatively simple sensor construction, enabling accurate detection of membrane tumbling motion.
3Measurement precision
If two figure-8 shaped detection coils are used to detect tumbling along perpendicular axes, then tumbling detection precision is improved, but device complexity increases
Solution Approach 1:
The patent designs the detection coils with a figure-8 shape that serves multiple functions: detecting tumbling along both perpendicular axes simultaneously, and potentially serving as damping coils as well. This multi-functionality reduces the need for separate detection and damping systems, balancing improved measurement precision with controlled device complexity.
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 solution effectively prevents membrane tumbling without adding mechanical components, ensuring consistent damping performance across different conditions and improving sound quality by reducing total harmonic distortion.
Implementation Method 1
The magnetic flux of the magnet system of the speaker will induce a voltage in both coils depending of the actual position of the coil with respect to the magnet system
Implementation Method 2
A damping coil may be used to feed-in the detection signal from the detection coils to electrically damp tumbling of the membrane
Data Source
AI summary
The invention relates to a new audio transducer for mobile devices, in particular a micro speaker for use in mobile phones, tablets, gaming devices, notebooks or similar devices, that comprises two figure-8 shaped coils to compensate tumbling passively or to detect and compensate actively rocking modes of the membrane along the two axes perpendicular to the axis of piston-wise movement of the membrane using a detection coil and a damping coil per axis. An amplifier may be used to amplify the detection signal in order to increase the damping effect. Electrical rocking mode compensation replaces state of the art damping mechanisms which are based on damping materials added in the moving part of the membrane. Due to the independence of environmental conditions electrical damping outperforms existing damping techniques.