Acoustic Device Flat Diaphragm Dipole Sound Spillage
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Solution Overview
Problem
Open audio devices experience significant sound spillage due to the placement of acoustic transducers away from the ear, which detracts from their usefulness and desirability.
Innovation Solution
The electro-acoustic transducer features a flat diaphragm with front and rear acoustic radiation, supported by a flexible structure and a magnetic circuit, with sound-emitting outlets positioned to emit sound out of phase, effectively creating a dipole-like acoustic behavior that minimizes sound spillage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the acoustic transducer is spaced from the ear in open audio devices, then the user can be more aware of the environment, but sound spillage increases and can be heard by others
Solution Approach 1:
The acoustic transducer is divided into two separate sound-emitting outlets: a first outlet for front acoustic radiation and a second outlet for rear acoustic radiation. This segmentation allows independent control and optimization of sound emission from each face, enabling the device to deliver sound to the ear while minimizing spillage to the environment.
Solution Approach 2:
The patent applies preliminary anti-action by emitting rear acoustic radiation from the second outlet that is out of phase with the front acoustic radiation. This pre-configured opposite-phase emission creates destructive interference for spilled sound waves in the environment, actively canceling unwanted sound before it can be heard by others, while maintaining effective sound delivery to the user's ear.
2Adaptability or versatility
If the acoustic transducer is spaced from the ear, then open audio device functionality is achieved, but the sound pressure ratio to spilled sound decreases
Solution Approach 1:
The patent transitions from conventional single-direction sound emission to three-dimensional bidirectional sound emission by utilizing both the front and rear faces of the diaphragm. The first outlet emits front acoustic radiation in one direction while the second outlet emits rear acoustic radiation in the opposite direction, creating a dipole-like acoustic field that improves sound pressure delivery to the ear while reducing environmental spillage through spatial distribution.
Solution Approach 2:
The out-of-phase rear acoustic radiation emitted from the second outlet creates preliminary anti-action that cancels spilled sound waves in the environment through destructive interference. This approach maintains open audio device functionality while improving the sound pressure ratio by reducing the energy of spilled sound relative to the sound delivered to the user's ear.
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 configuration achieves a greater ratio of sound pressure delivered to the ear to spilled sound, enhancing the performance of open audio devices by reducing unwanted sound leakage.
Implementation Method 1
a voice coil that is exposed to the magnetic flux and is configured to move the diaphragm up and down along a radiation axis
Implementation Method 2
the diaphragm configured to radiate front acoustic radiation from its front face and into a front acoustic volume defined between the front face of the diaphragm and the front face of the housing and rear acoustic radiation from its rear face
Implementation Method 3
a magnetic circuit that defines a path for magnetic flux of the primary magnet
Data Source
Figure 1~2
Figure 3A~3C
Figure 4A~4B
AI summary
An open audio device having a housing with opposed first and second ends, a flat diaphragm configured to radiate out-of-phase front and rear acoustic radiation, structure supporting the diaphragm so it can move relative to the housing, a primary magnet adjacent to the diaphragm, a magnetic circuit defining a path for magnetic flux, a voice coil exposed to the magnetic flux and configured to move the diaphragm along a radiation axis normal to the diaphragm, and first and second sound-emitting outlets, wherein the first outlet is in or proximate the first end of the housing and acoustically coupled to the front face of the diaphragm to emit front acoustic radiation into an acoustic space, and wherein the second outlet is in or proximate the second end of the housing and acoustically coupled to the rear face of the diaphragm to emit rear acoustic radiation into the same acoustic space.