Keyboard Instrument Soundboard Vibration Isolation
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Solution Overview
Problem
The vibration characteristics of a soundboard in acoustic keyboard instruments are adversely affected by the installation of heavy components, such as speakers, leading to a deterioration in the intrinsic sound quality.
Innovation Solution
An excitation unit with a vibration member connected to the soundboard and a main body, generating attraction or repulsion forces in response to a drive signal, is used to vibrate the soundboard while minimizing the load on the soundboard, and a controlling unit manages a stopper to allow or prevent hammer strikes, enabling selective sound generation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a speaker is installed directly on the soundboard to generate vibration sound, then the electronic piano can produce enriched acoustic low-pitched sounds, but the weight of the speaker changes the vibration characteristics of the soundboard and deteriorates the intrinsic sound quality
Solution Approach 1:
The patent introduces an intermediary structure (electromagnetic drive body) between the speaker and the soundboard. The drive body includes a vibration plate that couples the speaker output to the soundboard, acting as a mediator that transmits vibrations while isolating the weight of the speaker from directly loading the soundboard structure.
Solution Approach 2:
The system is divided into separate functional components: the speaker unit, the electromagnetic drive body with vibration plate, and the soundboard. This segmentation allows the heavy speaker to be mounted on the drive body structure rather than directly on the soundboard, separating the weight-bearing function from the vibration-transmission function.
2Adaptability or versatility
If heavy objects or devices are installed on the soundboard, then additional functions can be added to the keyboard instrument, but the vibration characteristics of the soundboard are changed largely and the intrinsic sound quality deteriorates
Solution Approach 1:
The electromagnetic drive body serves as a mediator structure that supports additional devices (speaker, control units) without transmitting their weight directly to the soundboard. The vibration plate within the drive body isolates the soundboard from external mass loading while still transmitting acoustic vibrations effectively.
Solution Approach 2:
The drive body structure is designed with asymmetric mass distribution where the heavy components are positioned on the frame structure rather than on the soundboard itself, creating an asymmetric loading pattern that protects the soundboard's vibration characteristics while enabling functional expansion.
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 solution maintains the soundboard's vibration characteristics, enriching the acoustic sound quality by allowing for various sound generation modes, including acoustic and electronic sound combinations, without impairing the instrument's original performance.
Implementation Method 1
an excitation unit (50) including a vibration member (51, 81) connected to the soundboard (7) and a main body (52, 82) heavier than the vibration members, the excitation unit (50) adapted to generate at least one of attraction force and repulsion force between the vibration member and the main body in response to a drive signal supplied thereto to vibrate the vibration member
Data Source
AI summary
In a predetermined sound generation mode, a drive signal having a frequency characteristic corresponding to an operated key is supplied to an excitation unit 50 provided on a soundboard (7). In response to a mechanical vibration generated by the excitation unit (50), the soundboard (7) is vibrated so as to generate an acoustic vibration sound corresponding to the operated key. The excitation unit (50) is supported by a supporting unit (55) such that less or no load of the excitation unit except a vibration member (51) vibrated in response to the drive signal is applied to the soundboard (7). Thus, only a load of the vibration member (51) which is a very light portion of the excitation unit (50) is applied to the soundboard (7), thereby vibration characteristics of the soundboard (7) being hardly affected. There is provided a sounding body (5) to be struck by a hammer (4) in response to the operation of the key. When a sound damping mode is selected, a stopper (40) is permitted to prevent the hammer from striking the sounding body (5). Consequently, sound generation based on the sounding body and sound generation based on the vibration of the soundboard can be combined selectively.