Ink Dot Overlap Prediction for High-Resolution Print Heads
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Solution Overview
Problem
Inkjet printing technologies face challenges in accurately predicting the overlapping state of ink dots on paper, leading to white streaks due to misalignment and varying dot diameters, which affects print quality, especially with high-resolution print heads having numerous nozzles.
Innovation Solution
An image processing apparatus and method that generates nozzle characteristic information by analyzing luminance data from printed chart patterns, determining the dot formation state, and adjusting dot patterns to prevent white streaks by changing dot sizes or patterns based on predicted overlap conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-pass method is adopted to achieve high-speed printing, then printing speed is improved, but white streaks occur due to ink dot misalignment and positioning errors
Solution Approach 1:
The patent applies preliminary action by measuring the actual dot positions and diameters of ink dots before final printing occurs. Test patterns are printed and scanned to obtain measurement data, which is then used to calculate correction values for dot position and size. These correction values are stored and applied to subsequent printing operations, allowing the system to compensate for positioning errors in advance rather than attempting to control precision during the high-speed single-pass printing process itself.
Solution Approach 2:
The patent changes parameters by dynamically adjusting the image data based on measured dot characteristics. The system calculates correction values for dot position (shift amount) and dot size (diameter) from measurement data, then applies these corrections to the image data before printing. This involves modifying pixel values and dot placement coordinates based on the measured deviations, thereby compensating for systematic positioning errors while maintaining high printing speed.
2Measurement precision
If the number of nozzles is increased to achieve high resolution (e.g., 1,200 dpi), then printing resolution is improved, but it becomes difficult to control the landing position and dot diameter of each ink droplet
Solution Approach 1:
The patent implements feedback by measuring the actual dot positions and diameters of ink dots after printing test patterns, then using these measurements to calculate correction values that are fed back into the image processing system. The measurement data from scanning test patterns is processed to obtain actual dot center positions and diameters, which are then used to compute correction values stored in lookup tables. These correction values are applied to subsequent printing operations, creating a closed-loop feedback system that continuously improves dot placement accuracy despite the high number of nozzles.
Solution Approach 2:
The patent replaces direct mechanical control of individual nozzle output with an optical measurement and computational correction approach. Instead of attempting to mechanically control each of the 1,200 nozzles to achieve perfect dot placement, the system prints test patterns, scans them to measure actual dot characteristics, computationally calculates correction values, and applies these corrections to the image data. This substitution of direct mechanical control with optical measurement and computational processing makes precision achievable despite the large number of nozzles.
3Quantity of substance
If ink dots from adjacent nozzles are positioned close together to maintain high density, then printing density is improved, but the overlap state of dots becomes difficult to predict and control
Solution Approach 1:
The patent replaces direct control of dot overlap through mechanical positioning with an optical measurement and computational correction approach. Test patterns with closely spaced dots are printed and scanned to measure actual dot positions and overlap states. The measurement data is processed to obtain actual dot center positions and diameters, which are then used to compute correction values for position and size. These corrections are applied to subsequent printing operations, enabling accurate prediction and control of dot overlap states even when nozzles are positioned close together for high density.
Data Source
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AI summary
To predict more accurately whether ink dots formed on the surface of paper by two nozzles arranged in a nozzle row and located at positions close to each other overlap. A luminance amount for each unit area surrounding each chart is derived from scanned data obtained by reading (S503) results of printing a plurality of charts (two-dot line chart corresponding to a nozzle pair of a nozzle of interest and a neighboring nozzle thereof among the plurality of nozzles) associated with a plurality of nozzles respectively (S504). Then, based on the luminance amount for each unit area, the dot formation state in a dot formation line by the plurality of nozzles is determined (S505).