Spectro-Camera Nozzle Calibration for Uniform Inkjet Density
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Solution Overview
Problem
Inkjet printing systems face challenges in achieving uniform density in solid areas due to manufacturing variability and other causes, leading to color differences that are difficult to measure and correct.
Innovation Solution
A printing system uses a spectrophotometer to measure spectral data, which is converted to density values and stored in a three-dimensional look-up table, allowing the system to accurately calibrate each nozzle's intensity for uniform color distribution without integrating the spectrophotometer physically in the printing system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple printheads with multiple nozzles are used to print solid areas, then printing productivity is improved, but density uniformity deteriorates due to manufacturing variability
Solution Approach 1:
The patent applies local quality by creating individual intensity value profiles for each nozzle based on its specific performance characteristics. The system measures and calibrates each nozzle separately, assigning unique intensity values that compensate for manufacturing variations. This ensures that each nozzle contributes uniformly to solid area density despite inherent differences in nozzle performance.
Solution Approach 2:
The system changes the intensity parameter for each nozzle based on measured density values. By adjusting the intensity values individually for each nozzle according to its specific performance, the system compensates for manufacturing variability and achieves uniform density across all nozzles while maintaining high productivity.
2Measurement precision
If a spectrophotometer is integrated into the printing system to measure color accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses a copy approach by creating a digital look-up table that stores the relationship between intensity values and measured density values for each nozzle. Instead of physically integrating a spectrophotometer into the printing system, the system captures spectral measurements during calibration and stores them as reference data. This allows the system to achieve spectrophotometer-level measurement precision through software-based colorimetric conversions without the complexity of physical integration.
Solution Approach 2:
The system introduces an intermediary look-up table that mediates between the printing system and spectral measurement requirements. The look-up table stores pre-measured density values obtained using a spectrophotometer, allowing the system to reference accurate spectral data without requiring the spectrophotometer to be physically present during normal printing operations.
3Stability of the object's composition
If intensity values are calibrated for each nozzle to achieve uniform density, then color consistency is improved, but calibration time increases
Solution Approach 1:
The system performs preliminary calibration actions by measuring and determining intensity values for each nozzle before actual printing operations begin. The look-up table is pre-populated with density measurements and corresponding intensity corrections, allowing the system to achieve color consistency without time-consuming calibration during production printing.
Solution Approach 2:
The system implements dynamic calibration capabilities that allow intensity values to be adjusted based on real-time performance monitoring. The system can update the look-up table with new measurements as nozzles wear or performance changes, maintaining color consistency over time without requiring complete recalibration.
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 method improves color accuracy and consistency, reducing printing artifacts like banding and color shifts, and enhances overall print quality by ensuring precise intensity calibration of each nozzle.
Implementation Method 1
a spectrophotometer to measure spectral data, which is converted to density values
Data Source
AI summary
Apparatuses, methods, and systems for achieving uniform density in solid areas of an image printed by multiple printheads having multiple nozzles are disclosed. A printing system receives a print job that includes solid color areas associated with uniform color values. An array is determined, where the array maps the uniform color values to density values measured using a spectrophotometer. Using this array, a template is obtained from a raster image processor of the printing system to map the density values to intensity values for the printer nozzles. The template is used to determine the intensity value for each nozzle based on the corresponding uniform color value's density. The printing system prints the image according to the determined intensity values, achieving uniform color distribution across the printed image.