Tuning Fork Reed Pairs for Compact Music Box Wristwatch

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Solution Overview

Problem

Existing music box wristwatch keyboards face challenges in reducing component size while maintaining varied melodies, good sound quality, and high sound levels, as internal friction increases with size reduction, affecting blade vibration duration and acoustic performance.

Innovation Solution

A keyboard comprising reed pairs configured as tuning forks, where activation of one blade causes longitudinal vibration propagation to the other, enhancing acoustic intensity and sonic purity by guiding vibrations to a radiating part, such as a plate or acoustic membrane.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the size of keyboard components is reduced to fit a watch, then the music box can be miniaturized for wristwatch application, but the vibration duration of activated blades becomes short due to increased internal friction relative to effective mass

Engineering Contradiction:
Improvesize of music moduleVSAvoidvibration duration of blades
Core Design Contradiction:
Volume of moving objectVSDuration of action of moving object

Solution Approach 1:

The patent combines two blades into a paired arrangement where they can vibrate together. When one blade is activated, it couples with its paired blade to create a combined vibrating system. This merging of two blades into a functional unit increases the effective mass participating in vibration, thereby extending vibration duration despite the miniaturized size of individual blades.

Inventive Principle:
Principle #5Merging (Combining)

2Volume of moving object

If the size of keyboard components is reduced to fit a watch, then the music box can be miniaturized for wristwatch application, but the sound level and acoustic performance deteriorate

Engineering Contradiction:
Improvesize of music moduleVSAvoidsound level and acoustic intensity
Core Design Contradiction:
Volume of moving objectVSIllumination intensity

Solution Approach 1:

By pairing two blades together, the system combines their acoustic output. When both blades in a pair vibrate simultaneously, their sound waves combine constructively, producing higher acoustic intensity than a single blade could achieve alone. This merging effect compensates for the reduced size of individual blades in the miniaturized watch application.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes mechanical vibration principles by arranging blades in pairs that can resonate together. The paired blades are designed to vibrate at specific frequencies, creating sustained oscillations that enhance sound production. The vibration coupling between paired blades amplifies the acoustic output, maintaining high sound levels despite the compact size constraints of a wristwatch music module.

Inventive Principle:
Principle #18Mechanical vibration

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 improves acoustic intensity and sonic purity by propagating a single eigenmode of vibration from each reed pair to radiating parts, optimizing sound production in a compact music box wristwatch design.

Implementation Method 1

By the activation of a blade of a pair of blades, a vibration propagation also occurs for the other blade of the pair thanks to a longitudinal wave

Methodology Applied
Scientific EffectLongitudinal wave propagation: Vibration

Data Source

PatentEP2482275B1Keyboard for musical box and musical box including said keyboard
Publication Date: 2014.03.12 MONTRES BREGUET SA
  • EP2482275B1 patent drawingFigure 1
  • EP2482275B1 patent drawingFigure 2a~2c

AI summary

The keyboard (1) is designed for a music box in the form of a wristwatch. The keyboard consists of a set of parallel pairs of blades (3, 3'), which are connected at one end to a butt (2). Each pair of blades forms a tuning fork, where one of the blades (3') of the pair can be set into vibration by at least one pin of a musical module, with the vibration propagating to the other blade (3) of the pair via a longitudinal wave.