Reaction Force Generator Buckling for Piano Click Feel
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Solution Overview
Problem
Conventional rubber dome switches in electronic musical instruments struggle to generate a distinct reaction force peak during the key depression stroke, making it difficult to replicate the click feeling of an acoustic piano, as the deformation starts from a curved area and expands gradually, leading to an unclear position of the reaction force peak.
Innovation Solution
A reaction force generator with an elastic structure and dome, featuring an after stroke portion and a click generating portion, both inclined relative to the pressing direction, where the click generating portion has a higher inclination and undergoes buckling to create a sudden decrease in reaction force, positioned to generate a click feeling in the first half of the dome stroke, ensuring accurate timing with the sounding timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rubber dome switch is used as a key depression detecting mechanism, then the device structure is simple and easy to manufacture, but it is difficult to generate a distinct reaction force peak during the key depression stroke
Solution Approach 1:
The dome is divided into multiple functional portions: a click generating portion with high inclination that buckles to create a reaction force peak, and an after stroke portion with lower inclination that provides gradual deformation. This segmentation allows each portion to perform its specific function independently, achieving both ease of manufacture and precise reaction force characteristics.
Solution Approach 2:
Different portions of the dome are given different local qualities through varying inclination angles. The click generating portion has a larger inclination angle to generate a sudden reaction force peak, while the after stroke portion has a smaller inclination angle for gradual deformation. This local differentiation enables precise control of the reaction force peak position while maintaining overall structural simplicity.
2Device complexity
If the deformation of the wall portion starts from a curved area and expands gradually, then the structure is simple, but the position of the reaction force peak becomes unclear and cannot be accurately matched with sounding timing
Solution Approach 1:
The click generating portion is pre-configured with a specific high inclination angle and thickness distribution that causes it to buckle at a predetermined position during the key depression stroke. This preliminary design ensures that the reaction force peak occurs at the exact timing needed for acoustic piano replication, without requiring complex control mechanisms.
Solution Approach 2:
The inclination angle and wall thickness of the click generating portion are specifically optimized to control when buckling occurs. By adjusting these parameters, the reaction force peak can be positioned accurately in the key depression stroke to match the sounding timing, achieving precise timing control through parameter optimization rather than complex mechanisms.
3Ease of operation
If the click generating portion has a larger degree of inclination than the after stroke portion, then a distinct click feeling can be generated, but the dome must be precisely designed and manufactured
Solution Approach 1:
The dome features local quality differentiation where the click generating portion has a larger inclination angle and optimized wall thickness compared to the after stroke portion. This localized design concentrates the complexity only where needed for click generation, while other portions maintain simpler geometries, balancing click feeling quality with manufacturability.
Solution Approach 2:
Specific parameters such as the inclination angle and wall thickness of the click generating portion are optimized to achieve the desired click feeling. These parameters are designed within practical manufacturing tolerances, ensuring that the distinct click feeling can be achieved without requiring excessively tight manufacturing precision across the entire dome structure.
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
The solution effectively generates a distinct click feeling by positioning the reaction force peak in the first half of the key depression stroke, enhancing the operational feel of electronic musical instruments to match that of an acoustic piano.
Implementation Method 1
generates a reaction force by elastic deformation of the elastic structure and the dome in a pressing process
Implementation Method 2
the click generating portion undergoes buckling in the pressing process to cause a sudden decrease in a reaction force and generate a click feeling
Data Source
AI summary
In a key switch (10), an inner dome (Din) starts to deform once a distal end portion (21) of the inner dome (Din) comes into contact with a base surface (93a) after an outer dome (Dout) starts to deform. A thick portion (25) extending straight and having a uniform wall thickness in a click generating portion (CL) has the thickness less than or equal to the minimum thickness of a thick portion (23) of an after stroke portion (AF). The degree of inclination of the thick portion (25) with respect to a center line (C0) (direction of pressing) is larger than that of the thick portion (23) with respect to the center line (C0) (θc>θa). Before the after stroke portion (AF) undergoes large deformation, the click generating portion (CL) undergoes buckling to cause a sudden decrease in a reaction force and generate a click feeling.