Curved Surface Digital Printing Droplet Formation Control
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Solution Overview
Problem
Existing digital printing methods struggle to achieve precise and high-quality printing on three-dimensionally curved surfaces, particularly due to undefined printing conditions that hinder the formation of fine patterns or lines across curved transition areas between inclined surface areas.
Innovation Solution
The method ensures that liquid droplets from individually controllable outlet openings have sufficient time to form before reaching the surface, with the exit surface arrangement optimized relative to the curvature, allowing for well-defined printing and adaptation of liquid amounts to surface inclination, preventing tangential movement and enabling wide printing paths on curved surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a linear relative movement between print head and component is used for printing inclined surface areas, then printing speed and productivity are improved, but printing precision and definition deteriorate in curved transition areas
Solution Approach 1:
The patent transitions from linear relative movement to a dynamic printing process where the print head moves in curved paths that follow the contour of the transition area. The printing system dynamically adjusts the movement trajectory to match the surface geometry, enabling precise deposition of liquid droplets on curved surfaces while maintaining productivity through automated control.
Solution Approach 2:
The patent changes the printing parameters by adjusting the liquid amount, droplet size, and deposition frequency based on the local surface geometry. In transition areas, the system modifies these parameters to ensure proper droplet formation and adhesion, thereby maintaining printing definition despite the complex surface topology.
2Manufacturing precision
If the print head is positioned close to the curved surface to achieve fine patterns, then printing precision is improved, but the liquid droplets do not have sufficient time to form before reaching the surface
Solution Approach 1:
The patent applies preliminary action by allowing liquid droplets to form completely before they are deposited onto the surface. The system controls the ejection timing and trajectory so that droplets achieve their final spherical shape and stabilize in flight before impacting the substrate, ensuring both fine pattern precision and proper droplet formation.
Solution Approach 2:
The patent utilizes the temporal dimension by extending the flight path of liquid droplets in time and space. Instead of immediate deposition, the system allows droplets to travel through air for a controlled duration, enabling complete formation and stabilization before surface contact, thereby resolving the conflict between close positioning and formation time.
3Productivity
If liquid is sprayed at high speed to maintain productivity, then printing speed is improved, but liquid droplets change trajectory and printing definition deteriorates
Solution Approach 1:
The patent implements feedback control by monitoring the flight trajectory of liquid droplets and adjusting the ejection parameters in real-time. The system measures actual droplet paths and modifies spray velocity, angle, and timing to compensate for trajectory deviations, thereby maintaining both high printing speed and precise trajectory control on curved surfaces.
4Area of stationary object
If the exit surface is arranged parallel to the inclined surface to optimize printing coverage, then printing width is improved, but liquid droplets strike tangentially and print quality deteriorates
Solution Approach 1:
The patent applies asymmetry by orienting the exit surface at a non-parallel angle to the inclined surface. Specifically, the exit surface is positioned perpendicular to the direction of liquid ejection rather than parallel to the substrate, creating an asymmetric configuration that ensures droplets strike the surface at optimal angles for adhesion and pattern definition, thereby improving print quality while maintaining coverage.
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
This approach enables precise, high-quality printing on three-dimensionally curved surfaces with optimal print web width and minimal overlap or visible transitions, allowing for excellent print quality on large, uneven surfaces.
Implementation Method 1
These quantities of liquid emerge from the outlet openings in the form of a liquid column and, in the course of flight, transform into an essentially spherical droplet
Implementation Method 2
In the course of flight, the liquid column transforms into an essentially spherical droplet that reaches the surface to be printed
Implementation Method 3
The spraying of the liquid from the outlet openings is controlled by piezo elements
Data Source
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AI summary
Method for printing a curved surface (10) by means of a digital printing method, in the case of which method defined liquid quantities are ejected from a plurality of individually actuable outlet openings (16) which are arranged on a planar outlet surface (14) of a print head (12), which liquid quantities impact on the curved surface (10) as liquid droplets, in the case of which method the curved surface (10) and the outlet surface (14) are oriented with respect to one another in such a way that a region of the curved surface (10) is directed parallel to the outlet surface (14), wherein said region is at a minimum spacing B from the outlet surface (14) in the case of a convex curvature of the surface (10) and is at a maximum spacing C from the outlet surface (14) in the case of a concave curvature of the surface (10), wherein, during printing, only outlet openings (16) are actuated for outputting a liquid quantity, the spacing of which from the impact point of the liquid droplet which is output by them from the curved surface (10) lies between the minimum spacing B and the maximum spacing C, wherein the minimum spacing B is given by the clear distance which the liquid quantity which is ejected from the outlet opening (16) requires in order to form a liquid droplet, and the maximum spacing C exceeds the minimum spacing by a predefined distance t, along which a liquid droplet does not degenerate and the path of which liquid droplet runs in a rectilinear manner, as a result of which, in the case of a relative movement between the outlet surface (14) and the surface (10) perpendicularly with respect to the curvature of the surface (10), the surface can be printed with a web, the width X of which corresponds, in the case of a convex curvature of the surface (10), to the distance between the outlet openings (10) which are spaced apart in the direction of the curvature of the surface (10) with a maximum spacing C and, in the case of a concave curvature of the surface (10), corresponds to the distance between the outlet openings (10) which are spaced apart in the direction of the curvature of the surface (10) with a minimum spacing B.