Spectro-Camera Nozzle Calibration for Uniform Solid Ink 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 conventional methods struggle to accurately measure and correct.
Innovation Solution
A method involving a spectrophotometer to measure spectral values, which are converted to density values and stored in a look-up table, allowing the printing system to calibrate each nozzle's intensity accurately without integrating the spectrophotometer physically, ensuring uniform color distribution across the printed image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used to measure color density in solid areas, then the measurement process is simple, but the measurement precision is insufficient leading to inaccurate color correction
Solution Approach 1:
The patent uses a spectrophotometer to create a digital copy (spectral signature) of the printed solid area, which is then stored in a lookup table. This digital representation allows for precise measurement and correction without requiring the physical spectrophotometer to be integrated into the printing system during operation, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent performs preliminary measurement and characterization of each nozzle's color output using a spectrophotometer before actual printing. The spectral data is processed and stored in a lookup table in advance, enabling precise color correction during printing without requiring complex real-time measurement equipment, thus achieving high measurement precision while keeping the printing system relatively simple
2Measurement precision
If a spectrophotometer is physically integrated into the printing system for real-time measurement, then measurement precision improves, but device complexity and cost increase significantly
Solution Approach 1:
Instead of physically integrating a spectrophotometer into the printing system, the patent creates digital copies (spectral signatures) of the color output through preliminary measurements. These spectral data copies are stored in a lookup table and used during printing to guide color correction, achieving spectrophotometer-level precision without the complexity of physical integration
Solution Approach 2:
The patent introduces a lookup table as an intermediary between the printing system and spectral measurement data. The lookup table stores pre-measured spectral signatures and provides color correction guidance without requiring direct physical connection or integration of the spectrophotometer with the printer, thus maintaining measurement precision while reducing system complexity
3Reliability
If manufacturing variability is not corrected, then the printing process is fast and simple, but color consistency across different nozzles deteriorates
Solution Approach 1:
The patent performs preliminary characterization of each nozzle's color output and stores correction data in a lookup table before actual printing. During printing, the system simply queries the lookup table for correction values based on the intended color and nozzle position, enabling fast color-consistent printing without real-time measurement or complex adjustments
Solution Approach 2:
The patent implements a feedback mechanism where the lookup table provides correction values to each nozzle based on its measured performance characteristics. This feedback loop ensures that each nozzle compensates for its manufacturing variability, maintaining color consistency across all nozzles while keeping the printing process efficient through pre-computed correction data
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
Improves color accuracy and consistency, reduces printing artifacts like banding and color shifts, and enhances overall print quality by accurately calibrating nozzle intensities based on spectral measurements.
Implementation Method 1
measuring a set of targets using a spectrophotometer to obtain a set of spectral measurements
Data Source
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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.