Percussion Instrument Bottom Frame Grooves to Prevent Sink Marks

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Solution Overview

Problem

The formation of reinforcement ribs on the upper surfaces of the radial parts of a percussion instrument's bottom frame can lead to sink marks on the lower surfaces, deteriorating the appearance when the frame is made of resin.

Innovation Solution

The use of concave parts on the lower surfaces of the radial parts, which are formed as grooves extending radially, along with a reinforcement frame made of a more rigid material, to enhance the rigidity and appearance of the bottom frame.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If reinforcement ribs are formed on the upper surfaces of the radial parts, then the rigidity of the bottom frame is improved, but sink marks occur on the lower surfaces of the radial parts, deteriorating the appearance

Engineering Contradiction:
Improverigidity of bottom frameVSAvoidappearance of bottom frame
Core Design Contradiction:
StrengthVSShape

Solution Approach 1:

Instead of forming reinforcement ribs on the upper surface of the bottom frame, the invention forms concave parts on the lower surface. This inverted approach allows the reinforcement structure to be created on the opposite side, preventing sink marks on the visible upper surface while still providing the necessary rigidity enhancement to the radial parts.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The reinforcement feature is moved from the upper dimension (upper surface) to the lower dimension (lower surface) of the bottom frame. By creating concave parts on the lower surface rather than ribs on the upper surface, the invention utilizes the third dimension (depth/thickness) to achieve reinforcement without compromising the appearance of the visible surface.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-generated harmful factors

If multiple opening parts are formed in the sensor frame, then vibration release is improved, but the rigidity of the sensor frame is reduced

Engineering Contradiction:
Improvevibration releaseVSAvoidrigidity of sensor frame
Core Design Contradiction:
Object-generated harmful factorsVSStrength

Solution Approach 1:

The sensor frame is divided into multiple sections by forming opening parts between the radial parts. This segmentation allows vibration to be released through the openings while the radial parts themselves maintain structural integrity. The openings create distinct segments that facilitate vibration release without completely compromising the frame's rigidity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The frame structure is made non-uniform by adding radial parts with concave parts at specific locations. These localized reinforcements are positioned strategically to maintain rigidity where needed (in the radial parts) while allowing vibration release in the opening areas between them. Each region of the frame has different properties optimized for its specific function.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4485449B1Percussion instrument and bottom frame reinforcement method
Publication Date: 2026.01.14 ROLAND CORP
  • EP4485449B1 patent drawingFigure 1
  • EP4485449B1 patent drawingFigure 2A~2B
  • EP4485449B1 patent drawingFigure 3

AI summary

Concave parts (24a to 24c) formed on lower surfaces of radial parts (21) are formed in a groove shape extending from the side of a central part (20) of a bottom frame (2) toward an outer peripheral side in a radial direction. Accordingly, the formation of ribs in the radial parts (21) of the bottom frame (2) is not required, or the number of ribs that are formed can be reduced, while the rigidity of the bottom frame (2) (radial parts (21)) can be secured by the concave parts (24a). Thus, even in the case where the bottom frame (2) is formed by using resin molding, the sink marks generated in the radial parts (21) can be suppressed. Therefore, the bottom frame (2) can be reinforced by the concave parts (24a to 24c), while the appearance of the percussion instrument (100) can be improved.