Cross-Track Position Error Correction in Digital Printers
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Solution Overview
Problem
Digital printing systems with linear printheads face significant cross-track alignment errors between color channels, leading to objectionable misalignment issues, which existing methods struggle to address without complex and costly fixtures.
Innovation Solution
A digital printing system that includes a method for determining and correcting cross-track position errors by using a test target with alignment marks, capturing images, analyzing positions, and applying a cross-track position correction function to resample image lines, thereby reducing alignment errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex and costly fixtures are used to correct cross-track position errors, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical alignment fixtures with a digital image processing system that uses camera capture, coordinate analysis, and software-based correction algorithms to achieve precise cross-track alignment measurement and correction without mechanical intervention
Solution Approach 2:
The patent creates a digital copy of the physical alignment marks through camera imaging, then performs all alignment measurements and corrections on this digital representation, eliminating the need for physical measurement fixtures and manual alignment procedures
2Device complexity
If traditional alignment methods are used, then device complexity is reduced, but manufacturing precision deteriorates due to cross-track alignment errors
Solution Approach 1:
The patent introduces alignment marks as intermediary reference objects that mediate between the printing system and measurement system, enabling precise cross-track alignment measurement through their known geometric positions and measurable image coordinates
Solution Approach 2:
The patent implements a feedback loop where alignment mark positions are measured, compared against reference values, and used to generate correction data that is applied back to the printing system to eliminate cross-track alignment errors
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
The system effectively reduces cross-track alignment errors in digital printing, allowing for non-linear corrections and improved image quality without the need for expensive fixtures.
Implementation Method 1
an electrostatic latent image is formed on a photoreceptor by uniformly charging the photoreceptor and then discharging selected areas of the uniform charge to yield an electrostatic charge pattern corresponding to the desired image
Implementation Method 2
charged toner particles are brought into the vicinity of the photoreceptor and are attracted to the latent image to develop the latent image into a toner image
Implementation Method 3
using a digital image capture system to capture an image of the printed test target
Data Source
AI summary
A digital printing system having a linear printhead includes corrections for cross-track position errors. A data processing system implements a method for determining a cross-track position function which includes printing a test target including a plurality of alignment marks, automatically analyzing a captured image of the printed test target to determine a measured position for each of the alignment marks, comparing the measured positions for the alignment marks to reference positions to determine measured cross-track position errors, and determining a cross-track position correction function responsive to the measured position errors. The cross-track position correction function specifies cross-track position corrections to be applied as a function of cross-track position. A corrected digital image is determined by resampling the image lines of a digital image responsive to the cross-track position correction function.