Headphone Transducer with Segmented Voice Coil
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Solution Overview
Problem
Existing electroacoustic transducers for headphones with zigzag voice coils are inefficient due to areas of the voice coil extending beyond the magnetic field, and their design is not adapted to the human ear shape, leading to irrational sound distribution and increased headphone dimensions.
Innovation Solution
A transducer design featuring an oval or irregularly tapered membrane with a spiral voice coil part over closed magnets and a meander-shaped part over arc-shaped magnets, optimizing the magnetic field distribution and voice coil topology to maximize the active area, ensuring that 100% of the voice coil is within the magnetic field and adapted to the ear shape, with a pole area ratio of 55-60% for closed to arc-shaped magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If zigzag (meander-shaped) voice coils are used, then the membrane can be rectangular or oval, but areas of the voice coil extend beyond the magnetic field and are not involved in electroacoustic transduction, reducing efficiency
Solution Approach 1:
The voice coil is segmented into multiple conductive traces arranged in a specific topology that divides the coil area into active and inactive zones, allowing the active portions to be precisely positioned within the magnetic field while the inactive portions are minimized or eliminated
Solution Approach 2:
Different regions of the voice coil are designed with different functions: the central area contains the active conductive traces that interact with the magnetic field, while the peripheral areas are optimized to minimize energy loss and improve mechanical properties without compromising transduction efficiency
2Productivity
If round or oval membranes with spiral voice coils are used, then transduction efficiency improves as no conductor extends beyond the magnetic field, but the membrane shape is not adapted to the human ear auricle and increases headphone dimensions
Solution Approach 1:
The membrane is designed with an asymmetric shape that is adapted to the contours of the human ear auricle, replacing the traditional symmetric round or oval shape. This asymmetric geometry allows the membrane to conform to the ear's natural shape, reducing the required headphone volume while maintaining effective transduction area
Solution Approach 2:
The voice coil topology is designed in multiple dimensions with conductive traces arranged in complex patterns that maximize the active area within the magnetic field while accommodating the asymmetric membrane shape, effectively utilizing three-dimensional space to maintain efficiency in a compact form
3Ease of manufacture
If the membrane shape is not adapted to the human ear, then manufacturing is simpler, but the inner cavity of the earpiece becomes irrational in shape and headphone dimensions increase
Solution Approach 1:
The membrane geometry parameters are optimized to match the statistical data of human ear auricle shapes, using averaged anatomical measurements to define the membrane contours. This allows the membrane to be adapted to ear shape while maintaining manufacturability through standardized production processes for the defined geometry
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 design enhances sound pressure distribution, achieves a more uniform amplitude-frequency profile, and improves spatial sound image focusing at high frequencies by optimizing the direct and reflected sound waves within the ear canal, maintaining high energy efficiency and minimizing headphone volume.
Implementation Method 1
Permanent magnets create a magnetic field perpendicular to the current flowing in the flat conductor of the voice coil. By interacting they create a force that affects the membrane perpendicular to its surface and makes it vibrating and provides electroacoustic transduction
Data Source
Figure 1a~1d
Figure 2a~2c
Figure 3
AI summary
The invention relates to electroacoustic transducers of electrodynamic type intended for the use in headphones. More particularly, the invention relates to the type of electroacoustic electrodynamic transducers having a vibration membrane with the voice coil with conductors fixed thereon and located in a constant magnetic field of the magnetic system of the electroacoustic transducer. The electroacoustic transducer for headphones comprises a dielectric membrane with a flat voice coil, a flat magnetic system comprising magnetized closed magnets axially spaced in concentric relationship, mounted on at least one side of the membrane configured so that the magnetic field can interact with the voice coil, according to the invention, the magnetic system further comprises at least two arc-shaped magnets located above the closed magnets and curved in the direction opposite to the closed magnets, and the voice coil comprises at least one part, which is located in the area of closed magnets and follows the shape of closed magnets, and the second part, which is located in the area of arc-shaped magnets and is meander-shaped. The use of the combined magnetic system comprising closed, preferably ring-shaped, magnets located in the area of the ear canal of the human ear auricle and arc-shaped magnets located above the closed magnets and curved in the direction opposite to the closed magnets, with a certain ratio of pole areas, as well as the use of the respective topology of the voice coil with the part that follows the shape of closed magnets and the meander-shaped part located in the area of arc-shaped magnets allows to achieve improvement in qualities of electroacoustic transduction by expanding the range of reproducible frequencies and increasing the efficiency of the transducer while minimizing the internal volume of the earpieces of headphones.