Balanced Passive Radiator Diaphragm with Offset Active Drivers
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Solution Overview
Problem
Loudspeaker systems with passive radiators face issues of unwanted vibrations and size constraints due to unbalanced passive radiator assemblies and interference from active driver assemblies, which affect frequency response and weight distribution.
Innovation Solution
The design includes a configuration where passive radiator diaphragms are balanced by coupling active driver assemblies to each diaphragm, with the moving mass of the active driver assemblies equal to or complementary with the passive radiator diaphragms, and using compliant coupling mechanisms to reduce interference and vibrations, allowing for efficient low-frequency output in a compact form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If passive radiator assemblies are made larger to improve low-frequency output, then low-frequency performance is improved, but device size and weight increase
Solution Approach 1:
The patent balances passive radiator assemblies by positioning active drivers at offset locations on the diaphragm surface. The active drivers generate acoustic pressure that moves the passive radiator diaphragm, while their offset positioning creates counterbalancing forces that reduce unwanted vibrations and allow for more efficient low-frequency output without proportionally increasing overall device weight.
2Device complexity
If active driver assemblies are positioned centrally on passive radiator diaphragms, then structural simplicity is maintained, but interference between drivers occurs and vibrations increase
Solution Approach 1:
The patent positions active driver assemblies at lateral offsets from the center of the passive radiator diaphragm rather than at the central position. This asymmetric positioning prevents interference between the active driver diaphragm and passive radiator diaphragm, reduces unwanted vibrations, and allows the active drivers to effectively move the passive radiator without mechanical interference.
3Power
If passive radiator diaphragms are made heavier to improve low-frequency response, then low-frequency performance is improved, but device weight increases
Solution Approach 1:
The patent combines the active driver assembly with the passive radiator diaphragm by mounting the active driver directly to the diaphragm surface. The moving mass of the active driver assembly is balanced with the moving mass of the passive radiator assembly, allowing the active driver to effectively move the passive radiator diaphragm and improve low-frequency response without requiring the passive radiator alone to be excessively heavy.
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 reduces unwanted vibrations, maintains a compact size, and enhances low-frequency performance by balancing the moving masses of passive and active components, ensuring efficient sound production without excessive weight or interference.
Implementation Method 1
configured to move parallel to a first axis that extends through a center of mass of the first passive radiator diaphragm and orthogonal to the first wall in response to a pressure change in the acoustic chamber
Implementation Method 2
configured to radiate acoustic energy in a direction parallel to the first axis and through an opening in the second passive radiator diaphragm
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A balanced acoustic device includes an enclosure defining an acoustic chamber, a first passive radiator diaphragm having an active driver assembly and a second passive radiator diaphragm having a plurality of active driver assemblies that are laterally offset. The moving mass of the first passive radiator assembly is substantially equal to the moving mass of the second passive radiator diaphragm. The lateral offsets of the active driver assemblies in the second passive radiator diaphragm eliminate their interference within the enclosure with the active driver assembly of the first passive radiator diaphragm. Advantageously, a smaller distance between the two passive radiator diaphragms is allowed and therefore a smaller enclosure is possible.