Flat Field Density Correction in Inkjet Printing Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Commercial inkjet printing systems face challenges in fabricating uniformly sized nozzles, leading to non-uniform ink laydown characteristics and unpredictable variations in dark and light density regions, resulting in waste and increased costs due to the need for extensive corrections across large print media lengths.
Innovation Solution
A printing system incorporating integrated imaging systems that capture images of printed content, using motion encoders to trigger image sensors, and processing devices to perform flat field and density correction by averaging pixel data and adjusting print masks to ensure uniform density, thereby correcting density variations in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple nozzle plates with precisely sized and spaced nozzles are used to increase printing capacity, then the printing system can handle larger print media and higher volume output, but manufacturing precision deteriorates due to the difficulty of fabricating uniformly sized nozzles across 12,000 to 30,000 nozzles
Solution Approach 1:
The printing system divides the large-scale printing task into multiple nozzle plates, each containing numerous nozzles. This segmentation allows the system to handle large print media (up to 52 inches wide) and high volume output while managing the complexity of nozzle fabrication across multiple separate plates rather than requiring all nozzles to be perfectly uniform across a single plate.
Solution Approach 2:
The patent applies flat field correction and density correction by modifying printing parameters (ink quantity, droplet size, frequency) for individual nozzles based on measured density variations. This compensates for manufacturing non-uniformities by dynamically adjusting printing parameters to achieve consistent output density across all nozzles despite variations in nozzle dimensions.
2Productivity
If corrections for density variations are delayed, then the printing system can continue operating without interruption, but loss of substance increases due to waste of print media that cannot be used
Solution Approach 1:
The system performs flat field correction and density correction in real-time during the printing process rather than delaying corrections. The imaging system captures images of printed content, processes the images to identify density variations, and applies corrections to subsequent printing operations immediately, preventing waste before it occurs.
Solution Approach 2:
The patent implements a feedback loop where an imaging system continuously monitors printed output for density variations, and the system automatically adjusts printing parameters based on this feedback. This closed-loop control ensures corrections are applied promptly to maintain print quality and prevent waste of print media.
3Manufacturing precision
If an integrated imaging system is added to capture and process images for real-time correction, then manufacturing precision of the printing output is improved, but device complexity increases
Solution Approach 1:
The patent combines the imaging system, processing device, and printing system into an integrated solution. The imaging system is positioned to capture images of printed content directly from the printing press, and the processing device is integrated with the printing control system to immediately analyze images and adjust printing parameters. This merging reduces the complexity that would arise from separate, standalone systems by creating a unified real-time correction system.
4Productivity
If real-time image capture and processing is implemented to correct density variations, then productivity is maintained through continuous operation, but use of energy increases due to additional imaging and processing equipment
Solution Approach 1:
The imaging system and processing device operate continuously during printing operations, capturing images and applying corrections in real-time without interrupting the printing process. This continuous operation maintains productivity while the system efficiently manages energy consumption by processing images only when needed and applying corrections immediately to avoid waste.
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 corrects density variations across large print media lengths, reducing waste and costs by ensuring uniform ink laydown, maintaining print quality, and minimizing the need for extensive corrections.
Implementation Method 1
a folded optical assembly in the housing that receives the reflected light and transmits the light a predetermined distance
Implementation Method 2
an image sensor within the housing that receives the light and captures one or more images of the printed content on the moving print media
Implementation Method 3
at least one motion encoder that transmits an electronic pulse or signal proportional to a fixed amount of incremental motion of the print media
Data Source
AI summary
A printing system includes at least one linehead that jets ink onto a print media and an integrated imaging system that captures images of the content printed on the print media. Each linehead includes one or more printheads. A flat field correction method for the printing system includes one or more printheads printing a test block having a known print density on the print media and producing a density variation trace for each of the one or more printheads by capturing an image of each printed test block and averaging pixel data in a transport direction. A negative print mask is then produced for each printhead in the one or more printheads by inverting each density variation trace. Each negative print mask is added to, or subtracted from, respective print data values transmitted to each respective printhead in the one or more printheads.