Color Registration Measurement Using Harmonic Decomposition
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Solution Overview
Problem
Current color-to-color registration measurement techniques in multicolor printing systems, such as those used in xerographic and inkjet printing, are limited in achieving photo-quality output due to their inability to correct color misregistration beyond 40 microns, as they only consider simple average shifts and lack methods for higher-order error correction.
Innovation Solution
A method and system for measuring color-to-color registration in multicolor marking platforms that involve marking and detecting test pattern images using a reference and first color separation stations, determining registration measurements, and identifying repeatable error patterns to enable precise correction of color misregistration across process and cross-process directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current DC shift measurement and correction techniques are used, then the measurement system remains simple, but color-to-color registration precision is limited to approximately 40 microns
Solution Approach 1:
The patent segments the registration measurement into multiple frequency components (DC shift, first harmonic, second harmonic, etc.) rather than treating it as a single average value. This allows measurement of both simple DC shifts and complex periodic errors independently, achieving higher precision (10-15 microns) by capturing the full spectrum of registration errors across multiple test pattern images positioned at different locations.
Solution Approach 2:
The patent adds the frequency domain dimension to the traditional spatial measurement approach. By analyzing test pattern images at multiple locations and decomposing registration errors into frequency components (DC, 1st harmonic, 2nd harmonic), the system transforms a one-dimensional average shift measurement into a multi-dimensional analysis that captures both magnitude and periodic characteristics of registration errors.
2Manufacturing precision
If simple average DC shift correction is applied, then the correction process remains straightforward, but photo-quality output cannot be achieved due to limited registration precision
Solution Approach 1:
The patent performs preliminary measurement and characterization of periodic registration errors using test pattern images before actual printing. By identifying and quantifying repeatable periodic errors (first and second harmonics) in advance, the system can pre-calculate correction values that are applied to subsequent production printing, achieving photo-quality registration (10-15 microns) without adding complexity to the main printing process.
Solution Approach 2:
The patent implements a feedback loop where test pattern images are measured, periodic error patterns are identified, and correction values are fed back to adjust the marking system. This closed-loop approach continuously refines registration precision by comparing actual performance against targets and applying corrective adjustments, enabling photo-quality output while maintaining ease of operation through automated correction.
Data Source
AI summary
In one embodiment, a method of measuring color-to-color registration includes: a) marking test pattern images on an image receiving member using a reference color separation station and a first color separation station over a process direction span in relation to selected target media and a cyclic characteristic of a multicolor marking platform, b) detecting each test pattern image, c) determining a registration measurement associated with the first color separation in relation to the reference color separation for each test pattern image, and d) determining a repeatable registration error pattern associated with the first color separation and the selected target media in relation to the cyclic characteristic based at least in part on the registration measurements determined in c). In one embodiment, the multicolor marking platform includes a marking engine, a controller, an image receiving member, a sensor, color registration measurement logic, and repeatable registration error determining logic.