Leather Coating Deposition Using Electrohydrodynamic Inkjet

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for creating designs on jewelry, leather goods, and writing instruments, such as pad printing and inkjet printing, are limited by high production costs, tooling requirements, and inadequate resolution and finish, especially for small production runs and multiple colors.

Innovation Solution

A method using electrohydrodynamic inkjet deposition to apply droplets of various fluids with precise control, allowing for versatile and cost-effective production of decorative coatings with high resolution and finish, compatible with a wide range of materials and designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional inkjet printing is used for small production runs, then production cost is reduced, but manufacturing precision and surface finish deteriorate due to droplet diameter greater than 25 μm causing pixelated effect and orange peel effect

Engineering Contradiction:
Improvecost-effectiveness for small production runsVSAvoidsurface finish quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the key parameter of droplet diameter from conventional >25 μm to <10 μm through electrohydrodynamic inkjet technology. This parameter change enables high-resolution printing with sharp curved lines and superior surface finish while maintaining cost-effectiveness for small production runs. The electrohydrodynamic process allows precise control of droplet formation, eliminating the pixelated effect and orange peel effect associated with conventional inkjet printing.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional mechanical inkjet mechanisms with electrohydrodynamic inkjet technology. Instead of using mechanical pressure or thermal expansion to eject droplets, the system uses electrohydrodynamic forces to generate and control droplet ejection. This substitution enables precise control over droplet size and placement, achieving manufacturing precision comparable to pad printing while maintaining the flexibility and cost advantages of inkjet printing for small production runs.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If pad printing is used to achieve high aesthetic quality, then manufacturing precision is improved, but device complexity increases due to requirement of separate tool for each design

Engineering Contradiction:
Improveaesthetic qualityVSAvoidtooling requirements
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a universal electrohydrodynamic inkjet printing system that can produce multiple different designs using the same hardware tooling. By digitally controlling droplet ejection patterns, the system can switch between different designs, colors, and patterns without requiring physical tool changes. This multi-functionality eliminates the need for separate pad printing tools for each design while maintaining high aesthetic quality through precise droplet placement and superior surface finish.

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

Solution Approach 2:

The patent introduces dynamic control capabilities to the printing system, allowing real-time adjustment of droplet ejection patterns, frequencies, and positions. This dynamic control enables the same tooling to adapt to different design requirements on demand, replacing the static nature of conventional pad printing tools. The system can dynamically switch between designs and configurations without physical retooling, reducing device complexity while maintaining manufacturing precision.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If conventional inkjet printing is used with low viscosity fluids, then ease of manufacture is improved, but adaptability deteriorates due to limitation in types of fluids that can be used

Engineering Contradiction:
Improvefluid compatibilityVSAvoidfluid type variety
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent changes the viscosity parameter range compatible with the printing system from low viscosity only to a broad range including high viscosity fluids. The electrohydrodynamic inkjet technology generates electric fields that can effectively control and eject droplets of various viscosities by adjusting the ejection frequency and voltage parameters. This parameter adaptability allows the system to handle diverse fluid types including metallic, aqueous, polymeric, ceramic, adhesive, and oil-based fluids, significantly improving versatility while maintaining ease of manufacture.

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

Achieves high-quality decorative coatings with precise control over droplet size and placement, enabling cost-effective mass production of personalized items with superior aesthetics, including invisible authentication patterns and technical applications like lubrication and metallization.

Implementation Method 1

to deposit a coating on at least part of the rough draft of a droplet fluid by electrohydrodynamic inkjet

Methodology Applied
Scientific EffectElectrohydrodynamic inkjet: Electrohydrodynamics

Data Source

PatentEP4674633A1Improved method for manufacturing a leather piece
Publication Date: 2026.01.07 RICHEMONT INTERNATIONAL SA
  • EP4674633A1 patent drawingFigure 1~3
  • EP4674633A1 patent drawingFigure 4~5
  • EP4674633A1 patent drawingFigure 6~7

AI summary

The invention relates to a method for manufacturing a part (2) comprising a step of depositing a coating (2D) using a droplet fluid (12A) by electrohydrodynamic inkjet.