Keyboard Support Assembly with Integrated Repetition Lever Hinge

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Solution Overview

Problem

The complex assembly of acoustic piano components, particularly the support assembly, leads to prolonged manufacturing time and high costs, while simplifying the structure to reduce costs can significantly alter the touch feeling during key operation.

Innovation Solution

A support assembly for a keyboard apparatus is designed with a reduced number of components and a simplified structure, incorporating a repetition lever hinge and torsion coil spring, which maintains the touch feeling similar to a grand piano by optimizing the rotation and contact points of the hammer shank and repetition lever, thereby achieving a double escapement mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the support assembly uses a conventional complex structure with multiple components, then the touch feeling is maintained, but the manufacturing time and cost increase

Engineering Contradiction:
Improvetouch feelingVSAvoidmanufacturing time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent combines multiple components into an integrated support assembly structure. The support, repetition lever, and escapement mechanism are merged into a unified structure that maintains the required touch feeling while reducing the number of separate parts, thereby simplifying assembly and reducing manufacturing time.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The support assembly is designed to perform multiple functions within a single integrated structure. It simultaneously provides support, enables repetition lever movement, and implements the escapement mechanism, eliminating the need for separate components for each function and thus reducing overall complexity and assembly time.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of manufacture

If the support assembly structure is simplified to reduce manufacturing cost, then the assembly process is simplified, but the touch feeling is significantly altered

Engineering Contradiction:
Improvemanufacturing costVSAvoidtouch feeling
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by maintaining complex, precision-engineered features only in the critical areas that directly affect touch feeling (such as the repetition lever contact points and escapement mechanism), while simplifying non-critical structural elements. This selective approach reduces overall manufacturing cost while preserving the essential tactile characteristics.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent optimizes specific geometric parameters and material properties of the support assembly to achieve the desired touch feeling with a simplified structure. By carefully adjusting angles, dimensions, and contact surface characteristics, the design maintains authentic piano touch characteristics while using fewer and simpler components.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If the number of components is reduced, then the assembly complexity decreases, but the structural stability may be compromised

Engineering Contradiction:
Improveassembly complexityVSAvoidstructural stability
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The support assembly is segmented into functional modules that are integrated but can be analyzed separately. The support body, repetition lever, and escapement components are distinct functional units within the integrated structure, allowing for simplified assembly while maintaining structural integrity through modular design principles.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs composite construction methods where multiple materials or structural layers are combined within the support assembly. This composite approach provides enhanced structural stability and rigidity while using fewer overall components, as the composite structure itself provides the necessary strength and stability that would otherwise require additional bracing or support elements.

Inventive Principle:
Principle #40Composite materials

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 reduces manufacturing costs while minimizing changes to the touch feeling, enhancing structural stability and simplifying the assembly process while maintaining the essential operation of the acoustic piano's action mechanism.

Implementation Method 1

incorporating a repetition lever hinge and torsion coil spring

Methodology Applied
Scientific EffectTorsion spring: Torsion Spring

Data Source

PatentEP3073485B1Support assembly and keyboard apparatus
Publication Date: 2021.08.18 YAMAHA CORP
  • EP3073485B1 patent drawingFigure 1
  • EP3073485B1 patent drawingFigure 2
  • EP3073485B1 patent drawingFigure 3A~3C

AI summary

A support assembly includes a support (210) rotatably disposed with respect to a frame (290, 920), a repetition lever hinge (220) mounted to the support (210), and a repetition lever (240) supported by the repetition lever hinge (220) and rotatably disposed with respect to the support (210), wherein the repetition lever (240) has a contact surface and the contact surface contacts a hammer shank roller (315) provided to a hammer shank (310) for rotating a hammer (320), and the repetition lever hinge (220) is mounted to the support in a mounting direction that crosses witha tangent-line direction of a line tangent to the hammer shank roller (315) at the contact between the hammer shank roller and the contact surface.