Plate Loudspeaker Modal Crossover Control for Bass and Transients
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Solution Overview
Problem
Conventional plate loudspeakers suffer from weak and reverberant bass response and temporal distortions, making them unsuitable for hi-fidelity audio applications, especially in thin, light electronics where form factor is critical, as they cannot easily be compensated for using equalization or inverse filtering due to spatially diffuse acoustic radiation.
Innovation Solution
An electrical backend control system, known as a modal crossover network, is used to tune the acoustic response of plates by processing signals into multiple frequency bands and assigning relative amplitudes to arrays of independently controlled drivers, allowing for flexible mechanical response tuning and improved frequency and transient characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If plate loudspeakers are used to reduce size and weight, then form factor is improved, but bass response becomes weak and reverberant
Solution Approach 1:
The patent segments the acoustic radiation function by using multiple independently controlled drivers distributed across the plate surface rather than a single driver. This allows different regions of the plate to be controlled independently to produce desired bass response while maintaining the lightweight plate structure.
Solution Approach 2:
The patent applies local quality by assigning different drive signals to drivers at different locations on the plate. The modal crossover network provides location-dependent drive signals to excite specific plate modes locally, enabling controlled bass response without requiring heavy materials or large plate dimensions.
2Device complexity
If a single small driver actuates the plate to reduce device complexity, then device complexity is reduced, but temporal distortion increases due to spread driving forces
Solution Approach 1:
The patent segments the driving function across multiple small drivers distributed on the plate surface. While this increases the number of drivers compared to a single driver approach, it enables precise temporal control by independently actuating different drivers to excite specific plate modes, thereby reducing temporal distortion.
Solution Approach 2:
The patent replaces the mechanical approach of using a single large driver with an electrical control system (modal crossover network) that processes signals and distributes them to multiple drivers. This electrical backend control system enables precise temporal control of plate vibration modes without requiring complex mechanical coupling.
3Ease of manufacture
If equalization and digital inverse filters are used to compensate for weak bass, then bass response is improved, but spatial diffusion properties limit effectiveness to select spatial points
Solution Approach 1:
The patent applies local quality by using multiple drivers at different locations on the plate, each controlled by location-dependent drive signals from the modal crossover network. This enables the system to produce consistent bass response across multiple spatial points simultaneously, rather than optimizing for a single listening position like traditional equalization approaches.
Solution Approach 2:
The patent achieves universality by designing the plate loudspeaker system to provide consistent audio reproduction across multiple spatial locations. The distributed driver array and modal crossover network enable the same bass enhancement to be experienced at various positions in the radiation zone, making the system universally effective rather than location-specific.
4Object-generated harmful factors
If materials with high internal damping are used to decrease reverberation, then reverberation is reduced, but bass response becomes weaker
Solution Approach 1:
The patent applies local quality by using multiple drivers at different locations on the plate, each controlled by location-dependent drive signals from the modal crossover network. This enables the system to produce consistent bass response across multiple spatial points simultaneously, rather than optimizing for a single listening position like traditional equalization approaches.
Solution Approach 2:
The patent achieves universality by designing the plate loudspeaker system to provide consistent audio reproduction across multiple spatial locations. The distributed driver array and modal crossover network enable the same bass enhancement to be experienced at various positions in the radiation zone, making the system universally effective rather than location-specific.
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 approach reduces the decay time of impulse responses and enhances the performance of plate loudspeakers as hi-fidelity devices without sacrificing bass response, offering better sonic reproduction for music and speech signals.
Implementation Method 1
A plate whose vibration is actuated by an electromagnetic coil driver or piezoelectric bending device
Implementation Method 2
A plate whose vibration is actuated by an electromagnetic coil driver or piezoelectric bending device
Implementation Method 3
DML because of the way it vibrates in complex combinations of resonant modes
Data Source
AI summary
Systems and methods of driving plate loudspeakers with different parameters based on frequency region in a way similar to typical cone driver crossover networks are described. These systems and methods may be implemented using arrays of independently controlled drivers which allow a designer to emphasize or de-emphasize certain modes in certain frequency bands. Tuning the characteristics of the plate's motion can also affect the acoustical properties in a larger space rather than just at a single location. The systems and methods described herein can grant a designer a degree of control over the characteristics and performance of the plate.