Elongated Loudspeaker Voice Coil Node Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional elongated loudspeakers experience resonance issues in the longitudinal direction, leading to peaks and dips in frequency characteristics, particularly at middle and high frequencies, which deteriorate sound quality.
Innovation Solution
A loudspeaker design featuring a vertically long flat diaphragm with voice coils connected in a manner that suppresses resonance modes, where the voice coils' long sides are positioned at specific nodes of the primary and secondary resonance modes in the short axis direction, ensuring they are parallel to the longitudinal direction of the diaphragm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the loudspeaker uses a conventional elongated structure with central driving, then the width can be narrowed to fit television sets, but resonance occurs easily in the longitudinal direction causing peaks and dips in frequency characteristics
Solution Approach 1:
The voice coil is divided into multiple independent units (first voice coil and second voice coil) positioned at different locations along the longitudinal direction. This segmentation allows independent control of vibration at different positions, enabling suppression of resonance modes that would otherwise occur with centralized driving.
Solution Approach 2:
Different portions of the diaphragm are driven with different characteristics by positioning voice coils at specific locations. The first voice coil is positioned to suppress primary resonance mode while the second voice coil suppresses secondary resonance mode, creating locally optimized vibration control throughout the diaphragm surface.
2Length of moving object
If the loudspeaker is designed to be thin for modern televisions, then the depth is reduced, but the structural complexity increases to maintain sound quality
Solution Approach 1:
Instead of increasing depth to accommodate complex magnetic circuits, the invention distributes multiple voice coils along the longitudinal dimension of the diaphragm. This dimensional redistribution allows thin design while maintaining the functionality of multiple voice coil units through careful spatial arrangement on the same plane.
3Use of energy by moving object
If the voice coil length is increased to cover more of the diaphragm, then the driving efficiency improves, but the positioning precision required to avoid resonance increases
Solution Approach 1:
The invention specifies precise parameter ranges for voice coil positioning, such as positioning the first voice coil within 10-30% from one end and the second voice coil within 70-90% from the same end along the longitudinal direction. These parameter specifications provide clear manufacturing targets that balance driving efficiency with resonance suppression effectiveness.
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 effectively suppresses resonance modes, extending the high-frequency limit and maintaining sound quality while allowing for slimming and thinning of the loudspeaker, resulting in a flat frequency characteristic and improved sound quality.
Implementation Method 1
an electric current is applied to the voice coil 106. With a driving current applied to the voice coil and a magnetic field around the voice coil 106, the voice coil bobbin 105 performs a piston motion, the diaphragm 109 vibrates
Data Source
AI summary
A loudspeaker comprises a diaphragm, an edge operable to support, on a frame, the diaphragm in such a manner that enables vibration thereof, and a voice coil operable to generate a driving force. The voice coil is of an approximate rectangular shape, and a length of a long axis direction of the voice coil is no less than 60% of a length of a long axis direction of the diaphragm. Positions of long sides of the voice coil to be fixed on the diaphragm are positions corresponding to nodes of a primary resonance mode in a short axis direction of the diaphragm, or in the respective vicinities thereof. Accordingly, it is possible to realize a high sound quality loudspeaker having a narrow width (elongated structure), but not easily causing resonance, thereby obtaining a flat frequency characteristic.