Inkjet Coating Head Positioning for Sharp Boundaries on Convex Surfaces

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Solution Overview

Problem

Existing coating devices using inkjet methods face challenges in achieving high resolution, uniform coating quality, and clear boundaries between different coating layers on complex surfaces, particularly on vehicles with convex curved surfaces.

Innovation Solution

A coating device with a robot-mounted inkjet head that adjusts its position and discharge parameters to ensure precise coating on convex surfaces, using multiple heads with varying discharge sizes, densities, and gap configurations to enhance contrast and stability of coating layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single inkjet head is used for coating, then the device structure is simple, but the coating uniformity and boundary sharpness deteriorate on complex surfaces

Engineering Contradiction:
Improvehead configurationVSAvoidcoating uniformity
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The coating system is divided into multiple independent inkjet heads (first inkjet head and second inkjet head), each responsible for different regions or layers. This segmentation allows each head to be optimized for specific coating requirements, improving overall coating uniformity and boundary sharpness while maintaining manageable device complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different inkjet heads are configured with different discharge characteristics (first head with first discharge characteristics, second head with second discharge characteristics) to match different local requirements of the coating surface. This local quality approach ensures that each region receives appropriately tailored coating parameters, enhancing coating precision and uniformity across the entire surface.

Inventive Principle:
Principle #3Local quality

2Area of stationary object

If the inkjet head is positioned far from the surface, then the coating coverage area is large, but the coating resolution and boundary sharpness deteriorate

Engineering Contradiction:
Improvecoating coverage areaVSAvoidboundary sharpness
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The coating area is divided into multiple zones handled by different inkjet heads positioned at different distances from the surface. Heads closer to the surface provide high-resolution coating with sharp boundaries for critical regions, while heads positioned farther away cover larger areas with appropriate resolution, achieving both large coverage and sharp boundaries in different regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system utilizes multi-dimensional positioning of multiple inkjet heads at different distances (Z-dimension) and positions (X-Y plane) to simultaneously achieve large coverage area and sharp boundaries. By distributing heads across different spatial dimensions, the system optimizes the trade-off between coverage area and boundary sharpness for different regions.

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

3Productivity

If the inkjet head moves quickly to increase productivity, then the coating speed is high, but the coating uniformity and resolution deteriorate

Engineering Contradiction:
Improvecoating speedVSAvoidcoating resolution
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The coating process is divided into multiple parallel streams using multiple inkjet heads, allowing different heads to operate at different speeds optimized for their specific tasks. This segmentation enables high overall productivity while maintaining high resolution in critical areas where heads move more slowly and discharge precision coating.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system employs dynamic control of inkjet head movement speeds and discharge parameters, adjusting velocity and discharge characteristics in real-time based on the specific coating requirements of different regions. This dynamic adaptation allows high-speed coating where uniformity is less critical while maintaining high resolution where boundaries and precision are required.

Inventive Principle:
Principle #15Dynamics

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

Improves coating quality by ensuring sharp boundaries, reduced unevenness, and enhanced appearance on convex surfaces, particularly on vehicle components like hoods and pillars.

Implementation Method 1

a head (10) including a nozzle surface (12) from which a coating material is discharged

Methodology Applied
Scientific EffectPressure-driven ejection: Pressure Gradient

Implementation Method 2

the head (10) moves while the coating material is discharged, thereby the to-be-coated object (30) is coated

Methodology Applied
Scientific EffectLiquid deposition: Deposition (physical)

Data Source

PatentEP4023343B1Coating device, coating film, and coating method
Publication Date: 2026.02.25 KYOCERA CORP
  • EP4023343B1 patent drawingFigure 1
  • EP4023343B1 patent drawingFigure 2
  • EP4023343B1 patent drawingFigure 3

AI summary

A coating device coats a coating region of a to-be-coated object having a convex curved surface. A coating device includes a head, an arm, and a controller. The head includes a nozzle surface. The arm holds the head. The controller controls movement of the head via the arm. A controller moves a head in a first direction along an end portion of a coating region in a posture in which a gap between a nozzle surface located on an end portion side of the coating region and a to-be-coated object is smaller than a gap between the nozzle surface located on a center side of the coating region and the to-be-coated object.