Keyboard Device Hammer Upper Limit Cushion Design
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Solution Overview
Problem
Conventional keyboard devices for keyboard instruments often result in unpleasant vibrations and variable key strokes due to strong repulsive forces from upper limit stoppers, leading to a 'sponge feeling' during key depression, especially when using medium or hard key striking forces.
Innovation Solution
A keyboard device design featuring a hammer upper limit cushion with flexibility and a harder key lower limit cushion, where the hammer upper limit cushion deforms to allow the key to reach its lowest position in contact with the key lower limit cushion, preventing repulsive forces from being transmitted to the key, thus providing a stable key stroke and eliminating unpleasant vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard upper limit stopper member is used to stop the swing lever, then the swing lever can be reliably stopped, but strong repulsive forces are generated causing unpleasant vibrations and sponge feeling
Solution Approach 1:
The patent applies beforehand cushioning by placing a cushioning member between the hammer and the upper limit stopper member. This cushioning member deforms to absorb the impact energy when the hammer strikes it, preventing the strong repulsive force from being transmitted to the key. The cushioning effect is prepared in advance, so when medium or hard key striking occurs, the harmful repulsive forces are already mitigated, eliminating the sponge feeling and unpleasant vibrations while maintaining reliable stopping.
Solution Approach 2:
The cushioning member serves as an intermediary between the hammer and the upper limit stopper member. Instead of the hammer directly contacting the hard stopper member, the cushioning member mediates the interaction by deforming under impact. This intermediary absorbs the shock and prevents the direct transmission of strong repulsive forces to the key, thereby resolving the contradiction between reliable stopping and harmful vibrations.
2Ease of operation
If the upper limit stopper member contacts the swing lever first, then the swing can be controlled, but the key cannot reach its lowest position causing variable key stroke length
Solution Approach 1:
The cushioning member is positioned to be contacted first by the hammer before the swing lever reaches the upper limit stopper member. This beforehand cushioning allows the hammer to deform the cushioning member during its swing, ensuring that the key can continue moving downward to reach its lowest position consistently. The cushioning member's deformation absorbs the impact energy gradually, allowing the key to complete its full stroke without being prematurely stopped, thus achieving consistent key stroke length.
3Reliability
If repeated contact with the upper limit stopper member occurs, then the swing lever stops reliably, but the contact portion deforms causing swing angle increase and key stroke change
Solution Approach 1:
The cushioning member is designed to be contacted first by the hammer during each swing, preventing direct repeated contact between the hammer and the hard upper limit stopper member. The cushioning member's material properties allow it to deform elastically and recover, absorbing impact energy without permanent deformation. This beforehand cushioning protects the contact portions from deformation, maintaining the structural stability and ensuring consistent swing angle and key stroke length over repeated use.
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 ensures an excellent touch feeling and stable key stroke without the 'sponge feeling' or unpleasant vibrations, regardless of the key depression force, as the key consistently reaches its lowest position in contact with the key lower limit cushion, maintaining consistent key stroke length.
Implementation Method 1
the hammer upper limit cushion is configured to have a predetermined flexibility that allows deformation of the hammer upper limit cushion itself
Implementation Method 2
the key lower limit cushion is formed to be harder than the hammer upper limit cushion
Data Source
AI summary
A keyboard device for a keyboard instrument, capable of obtaining excellent touch feeling and stable key stroke without giving sponge feeling or unpleasant vibration during key depression. The keyboard device includes a keyboard chassis, keys pivotally supported on the chassis, hammers swingably supported on the chassis and swinging along with key depression, a hammer upper limit stopper provided on a chassis rear end and contacted by a hammer rear end from below during key depression, and a key lower limit stopper provided on a chassis front end and contacted by front ends of the keys from above during key depression. The hammer upper limit stopper has predetermined flexibility that allows deformation of the hammer upper limit stopper such that after contact of a hammer during key depression, an associated key reaches its lowest position in a state in contact with the key lower limit stopper.