Watch Component Multilayer Coating for High-Chroma Color

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Solution Overview

Problem

Existing watch components struggle to express high-chroma color tones while maintaining aesthetic appeal and durability, as seen in technologies that rely on noble metals or multilayer films with limited color-adjusting capabilities.

Innovation Solution

A watch component featuring a multilayer film composed of oxide and fluoride layers, including a first color-adjusting film with a refractive index of 2.0 or more, a second color-adjusting film with a refractive index of 1.5 to less than 2.0, and a third color-adjusting film with less than 1.5, formed by dry plating, which enhances color expression and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a toning film is stacked on a base plate to adjust color tone, then aesthetic appeal is improved, but the ability to express high-chroma color tones deteriorates

Engineering Contradiction:
Improveaesthetic appealVSAvoidcolor tone expression capability
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The color-adjusting film is divided into three distinct layers with different refractive indexes (first layer: 2.0 or more, second layer: 1.5 to less than 2.0, third layer: less than 1.5). This segmentation allows each layer to contribute differently to optical interference, enabling high-chroma color expression while maintaining aesthetic appeal through the combined effect of all layers.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses a composite multilayer structure combining oxide layers and fluoride layers with specific refractive indexes. This composite material approach enables precise control over optical properties, achieving both aesthetic appeal and high-chroma color expression that cannot be obtained with single-material films.

Inventive Principle:
Principle #40Composite materials

2Stability of the object's composition

If noble metals are used as main material, then aesthetic appeal is improved, but cost and weight increase

Engineering Contradiction:
Improveaesthetic appealVSAvoidweight
Core Design Contradiction:
Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The invention replaces expensive noble metals with a multilayer film structure made of oxide and fluoride layers that can be formed by dry plating. This alternative provides comparable aesthetic appeal through optical interference effects while significantly reducing material cost and weight.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention changes the fundamental approach from using noble metal materials to using a multilayer film structure with controlled optical parameters (refractive indexes). By controlling the refractive indexes of each layer rather than relying on inherent noble metal properties, aesthetic appeal is achieved through optical design rather than material selection, reducing weight and cost.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If a multilayer film is used to cover the base material, then aesthetic appeal is improved, but the number of layers and complexity increase

Engineering Contradiction:
Improveaesthetic appealVSAvoidnumber of layers
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The color-adjusting film is segmented into three layers with specific refractive index ranges, which is the minimum number needed to achieve high-chroma color expression through optical interference. This segmented structure provides the necessary complexity to solve the technical problem while keeping the layer count minimal.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention controls the refractive index parameter of each layer to achieve the desired optical effect. By precisely controlling these physical parameters rather than adding more layers, the invention achieves high-chroma color expression with a minimal three-layer structure, balancing complexity and performance.

Inventive Principle:
Principle #35Parameter changes

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 enables the expression of high-chroma color tones with improved durability and aesthetic appeal by utilizing inorganic materials with high chemical stability, achieving chroma values of 30 or more with a minimal number of layers.

Implementation Method 1

the multilayer film includes a color-adjusting film that is composed of an oxide layer or a fluoride layer and that is formed by dry plating, and the color-adjusting film includes a first color-adjusting film having a refractive index of 2.0 or more, a second color-adjusting film having a refractive index of 1.5 or more and less than 2.0, and a third color-adjusting film having a refractive index of less than 1.5

Methodology Applied
Scientific EffectOptical interference: Interference

Data Source

PatentEP4485087B1Watch component and watch
Publication Date: 2026.02.25 SEIKO EPSON CORP
  • EP4485087B1 patent drawingFigure 1
  • EP4485087B1 patent drawingFigure 2
  • EP4485087B1 patent drawing

AI summary

A watch component includes a base material and a multilayer film covering at least a portion of the base material, wherein the multilayer film includes a color-adjusting film that is composed of an oxide layer or a fluoride layer and that is formed by dry plating, and the color-adjusting film includes a first color-adjusting film having a refractive index of 2.0 or more, a second color-adjusting film having a refractive index of 1.5 or more and less than 2.0, and a third color-adjusting film having a refractive index of less than 1.5.