Inkjet Nozzle Control for Curved Surface Printing
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Solution Overview
Problem
Inkjet printing systems face challenges in maintaining consistent ink droplet density when printing on curved surfaces due to varying nozzle velocities, leading to undesirable defects in the printed image, as existing methods like 2D linearization struggle with complex corrections for drop densities and ink mixing.
Innovation Solution
A method and system that define target jetting locations with a regular pitch, determine the maximum nozzle velocity, set an error distance, and provide a control signal with actuation events at a specific interval to ensure actual jetting locations deviate no more than twice the error distance from target locations, allowing for precise dot placement on curved surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a common drive signal is supplied to multiple nozzles with synchronized actuation events, then printing efficiency and productivity are improved, but manufacturing precision deteriorates when printing on curved surfaces due to varying nozzle velocities causing density variations
Solution Approach 1:
The patent applies local quality by allowing each nozzle to have individualized jetting timing adjustments based on its specific path and velocity characteristics, while still using a common drive signal framework. The controller selectively activates or deactivates specific nozzles based on real-time position and velocity data, enabling localized compensation for density variations without requiring separate drive signals for each nozzle.
Solution Approach 2:
The system dynamically adjusts which nozzles are activated for each actuation event based on real-time measurement of nozzle velocities and positions. The controller continuously updates the activation state of nozzles according to their current motion state, enabling adaptive compensation for velocity variations that occur during curved surface printing while maintaining the efficiency of common drive signaling.
2Manufacturing precision
If the actuation interval is reduced to limit the maximum distance between potential jetting locations, then manufacturing precision is improved by reducing error distance, but productivity deteriorates due to increased actuation frequency requirements
Solution Approach 1:
The patent implements partial action by selectively activating only those nozzles that are currently positioned within the acceptable error distance of their target jetting locations. Instead of requiring all nozzles to operate at a high frequency to ensure accuracy, the system activates only the necessary subset of nozzles for each actuation event, reducing the overall actuation frequency requirement while maintaining precision.
Solution Approach 2:
The system dynamically changes the activation parameter (on/off state) of individual nozzles based on their real-time position and velocity. By adjusting which nozzles are active rather than changing the fundamental actuation interval, the system maintains precision requirements while avoiding the productivity penalty of uniformly increasing actuation frequency across all nozzles.
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 ensures consistent dot resolution and density across curved surfaces by selecting appropriate actual jetting locations within a defined error distance, effectively correcting for variations in nozzle speed and preventing defects like dot gain and ink mixing issues.
Implementation Method 1
Such actuators include piezoelectric actuators for example
Data Source
AI summary
A method of controlling a system including an arrangement of at least two nozzles, wherein the arrangement and the shape move relative to each other, each nozzle traces a respective path on the shape, and each nozzle is configured to jet drops at actual jetting locations along the respective path of the nozzle. The method results in sequence of actuation events received from a control signal to be more frequent than would be needed for an arrangement printing on a flat surface to produce the required dot resolution. It is then possible to select which of the individual nozzles are to jet for a given actuation event from the sequence so that the actual jetting locations deviate from the target jetting locations by no ore than a define maximum error distance.