Piano Action Flat Contact Surfaces Let-Off Timing
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Solution Overview
Problem
Upright pianos face challenges in pinpointing the timing of hammer let-off, resulting in difficulties in finely adjusting string striking speed and lower sequentially touching capabilities compared to grand pianos, due to the hammer's center of gravity being near the fulcrum, leading to a small let-off load and increased touch weight when enhancing spring force.
Innovation Solution
The piano action features a wippen and jack with flat contact surfaces, where the regulating button contact surface comes into planar contact with the jack contact surface, increasing frictional resistance and let-off load, allowing for clearer let-off timing and touch weight differentiation, along with a hammer push-up rod prominence for additional resistance, and a jack made of reinforced thermoplastic resin for improved rigidity and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the hammer center of gravity is positioned near the fulcrum to maintain structural compactness, then the moment about the fulcrum produced by self weight is small, but the let-off load becomes relatively small making it difficult to pinpoint let-off timing
Solution Approach 1:
The patent applies local quality by creating a concentration of mass at the hammer head (远离fulcrum) while keeping the overall hammer structure compact. The hammer head is designed with increased weight relative to the shank, positioning the center of gravity away from the fulcrum to generate sufficient moment for clear let-off detection, while the balanced weight distribution maintains structural compactness suitable for upright pianos.
2Productivity
If the spring force is enhanced to improve sequentially touching capabilities, then the hammer returns faster to ready position, but the touch weight increases adversely affecting touch feeling
Solution Approach 1:
The patent applies parameter changes by optimizing the spring constant and pre-compression of the hammer spring to achieve the desired balance. The spring parameters are specifically tuned to provide sufficient restoring force for rapid hammer return (improving sequentially touching capabilities) while controlling the magnitude of force transmitted to the key during normal operation (maintaining acceptable touch weight and feeling).
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 enhances the clarity of let-off timing, allowing for finer adjustment of string striking speed and improves sequentially touching capabilities while maintaining a good touch feeling, achieving high playing performance with expressive power in a simple structure.
Implementation Method 1
the regulating button contact surface comes into planar contact with the jack contact surface, increasing frictional resistance and let-off load
Implementation Method 2
a jack made of reinforced thermoplastic resin for improved rigidity and conductivity
Implementation Method 3
the center of gravity of the hammer is positioned near the fulcrum of its swinging movements, resulting in small moment about the fulcrum of the swinging movements produced by the self weight of the hammer
Data Source
AI summary
An action for a piano is provided for clarifying a timing of let-off, improving the sequential touching capabilities, and consequently realizing high playing performance excellent in expressive power in a simple structure without adversely affecting the key touch feeling. The action for a piano swings a hammer in response to a touch on a key, and comprises a wippen pushed up by the key to pivotally move, a regulating button having a flat jack contact surface on the lower end, and a jack having a flat regulating button contact surface which comes into contact with the jack contact surface as the key is depressed. The jack comprises a molding made of a thermoplastic resin containing long fibers for reinforcement.