Flat Subwoofer Dual Membrane Stability
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Solution Overview
Problem
Existing flat subwoofer designs face challenges in achieving high sound pressure with minimal distortion due to the instability of flat membranes, which leads to distortion and excessive load, and previous solutions like folded membranes or dual surround constructions result in sound diffusion or power loss.
Innovation Solution
A flat subwoofer design featuring two interconnected membrane parts, where the rear membrane part is V or U-shaped, connected to a spring member, and the coil is positioned on a cylinder connected to the inner periphery of the rear membrane, providing stability and improved sound transmission with reduced distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a flat membrane is used to minimize construction size, then the extent along the sound emission axis is reduced, but the membrane becomes unstable causing distortion and excessive load
Solution Approach 1:
The membrane is divided into two separate parts: a front membrane part and a rear membrane part. The front membrane part maintains flatness for compact construction, while the rear membrane part provides structural support and stability. This segmentation allows each part to fulfill its specific function without compromise.
Solution Approach 2:
The rear membrane part is configured to extend in a direction substantially perpendicular to the sound emission axis, creating a multi-dimensional structure. This dimensional change allows the rear part to provide stability without increasing the construction depth in the sound emission direction.
2Stress or pressure
If the coil moves a long distance to provide sufficient sound pressure, then sound pressure is improved, but distortion and deformation increase
Solution Approach 1:
By segmenting the membrane into two parts with different functions, the front part can move freely to generate sound pressure while the rear part remains relatively stable to prevent distortion. This segmentation decouples the motion requirements from the stability requirements.
Solution Approach 2:
The rear membrane part acts as an intermediary between the coil assembly and the external environment. It provides a stable mounting base for the coil while allowing the front membrane part to move, thereby mediating between the need for coil movement and the need for structural stability.
3Stability of the object's composition
If two separate surrounds are used to maintain rigid membrane position, then membrane stability is improved, but power loss increases due to dampening
Solution Approach 1:
The membrane is segmented into two parts that are connected in a specific geometric configuration. This segmentation eliminates the need for dual surrounds while maintaining stability, as each membrane part can be secured with a single surround at its outer periphery.
Solution Approach 2:
The rear membrane part is configured with a curved or angled geometry (extending perpendicular to the sound axis), which provides structural rigidity and stability without requiring additional restrictive surrounds. This geometric configuration inherently resists deformation.
4Stability of the object's composition
If two surrounds are used to guide membrane movement, then membrane positioning is improved, but synchronization issues cause voice coil wobble
Solution Approach 1:
The membrane system is segmented into two parts that move in a coordinated manner due to their geometric connection. This segmentation with fixed geometric relationship ensures synchronized movement, preventing voice coil wobble while maintaining stable positioning.
Solution Approach 2:
The two membrane parts form a composite membrane structure where the combination of parts creates a unified, synchronized moving system. The geometric connection between parts ensures they move together as a coordinated unit, preventing differential movement that would cause coil instability.
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 achieves high sound pressure with minimal distortion, allows for a narrower air gap to enhance magnetic field strength, and operates within a wider frequency range with reduced weight and air resistance, resulting in improved sound quality and response time.
Implementation Method 1
the rear membrane part is connected to a spring member which spring member at least partly surrounds the driver
Implementation Method 2
a coil is arranged in an air gap, provided in a magnetic field, such that when the direction of the current through the coil changes direction, the magnetic field causes the coil to move back and forth in the air gap
Data Source
Figure 1
Figure 2~5
AI summary
Flat subwoofer (1) comprising a driver (10) in which a coil (2) is arranged in an air gap (3) in said driver, which coil is connected to a membrane (4,5), where said driver (10) i arranged on a chassis (11), characterised in that the membrane comprises two interconnected parts, a forward membrane part (4) and rear membrane part (5), where bot membrane parts (4,5) are substantially symmetrical around an axis (9) perpendicular t the membranes plane, where each membrane part has an outer and an inner periphery where said forward membrane part (4) along an outer periphery is connected to th chassis (11) by means of a surround (8), and where said rear membrane part (5) i connected to a spring member (15) which spring member at least partly surrounds th driver (10), and where the coil (2) is arranged on a coil cylinder (16), which cylinder i connected either to the inner periphery (13) of the rear membrane part (5) or to the inner periphery of the forward membrane part (4) in which case the forward and rear membrane parts (4,5) are connected, or to the connection between the forward membrane art and the rear membrane part.