Inkjet Printing on Curved Surfaces with Tone Value Calibration
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Solution Overview
Problem
Inkjet printing on curved surfaces often results in undesirable tone value fluctuations due to varying ink droplet density, leading to visible defects in the printed image.
Innovation Solution
A method and device that use a computer-controlled inkjet print head with nozzles to apply ink drops on a curved surface, involving data processing steps for calculating application locations, tiling, tone value calibration, and screening to ensure consistent droplet density and tone values, thereby avoiding defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a robot arm guides an inkjet print head along a curved surface to print an image, then the ability to print on three-dimensional objects is achieved, but tone value fluctuations and visible defects occur due to varying ink droplet density
Solution Approach 1:
The patent applies preliminary action by performing a coordinate transformation and calculating compensation values before the actual printing process. The control unit pre-calculates the relationship between robot arm position and print head nozzle position, and pre-determines compensation values for tone values based on predicted ink droplet density variations. This allows the system to compensate for curvature-induced defects before printing begins, maintaining tone value consistency while printing on curved surfaces.
Solution Approach 2:
The patent changes parameters by dynamically adjusting tone values and ink droplet density compensation based on the calculated relationship between robot arm position and print head position. The control unit modifies printing parameters (tone values, droplet spacing) as functions of the object's curvature and surface geometry, allowing consistent image quality across curved surfaces despite varying droplet density.
2Area of stationary object
If ink droplets are applied at varying density to match surface curvature, then complete surface coverage is achieved, but tone value fluctuations and visible defects occur
Solution Approach 1:
The patent implements feedback by using a camera to capture images of the printed object and comparing them with the target image. The control unit calculates differences between the captured image and target image, then uses this feedback information to adjust subsequent printing parameters. This closed-loop control compensates for tone value fluctuations and ensures consistent image quality across the entire curved surface.
Solution Approach 2:
The system performs preliminary scanning and measurement of the curved surface geometry before printing, allowing pre-calculation of compensation values for tone values and ink droplet density. This preliminary characterization of the surface enables the system to maintain consistent image quality while achieving complete surface coverage.
3Measurement precision
If the print head moves along the curved surface following the contour, then accurate positioning is achieved, but ink droplet density varies causing tone value fluctuations
Solution Approach 1:
The patent changes parameters by establishing a mathematical relationship between robot arm coordinates and print head nozzle coordinates through coordinate transformation. The system adjusts ink droplet density and tone values as dynamic parameters based on the local curvature and surface geometry at each position, maintaining consistent image quality while following the curved surface contour with high positioning accuracy.
Solution Approach 2:
The patent applies local quality by calculating and applying position-specific compensation values for ink droplet density and tone values at different locations on the curved surface. The control unit determines local surface geometry characteristics and adjusts printing parameters accordingly for each region, ensuring consistent image quality across the entire curved surface despite varying droplet density requirements.
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
Enables precise printing on any curved surface with reduced tone value fluctuations, resulting in visually appealing three-dimensional printed products with consistent image quality.
Implementation Method 1
a screen of ink drops is applied to the region to create print dots and wherein the screen is calculated by a computer and the ink drops are generated and applied to the region by a print head by using nozzles on a nozzle surface of the print head
Data Source
AI summary
A method for inkjet printing an image onto a curved region of an object surface includes applying a screen of ink drops to the region to create print dots, calculating the screen using a computer and generating and applying ink drops to the region using a print head having nozzles on a nozzle surface. The steps include a) providing data representing the print image, b) providing or calculating data representing the region, c) providing or calculating path data on paths for the print head or object, d) calculating application locations of ink drops using data from steps b) and c), e) calculating data based on tiling the region using data from step d), f) calibrating tone values using data from step e), g) screening the print image using data from step f), and h) printing the screened image onto the region. A device implementing the method is also provided.