Calibration Target Using NPAC Vectors for Drop Weight Sensitivity
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Solution Overview
Problem
Printers, especially page wide array (PWA) printers with multiple dies, face challenges in achieving accurate calibration due to variations in ink drop weight caused by temperature, humidity, and wear, which are not adequately addressed by current calibration methods and sensors, leading to visible color variations and difficulties in measuring small color differences.
Innovation Solution
The use of a calibration target with Neugebauer Primary area coverage vectors (NPacs) that maximize color change for given ink drop weight variations, allowing for the selection of ink combinations that are sensitive to drop weight changes, enabling more accurate detection of color variations and improved calibration accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration patches with standard color combinations are used, then the calibration process is simple, but the sensitivity to detect small color variations caused by drop weight changes is insufficient
Solution Approach 1:
The patent changes the parameters of the calibration patches by using specific Neugebauer Primary area coverage (NPAC) vectors with optimized ink combinations. These patches are designed to maximize color change in response to drop weight variations, thereby increasing measurement precision without requiring more complex measurement equipment
Solution Approach 2:
The calibration patches are pre-designed with known NPAC vectors that are calculated in advance to be highly sensitive to drop weight changes. This preliminary design of the calibration target allows the system to detect small color variations before actual printing calibration occurs, improving detection sensitivity without adding complexity to the measurement process
2Manufacturing precision
If standard calibration methods are used, then the process is straightforward, but visible color variations between multiple dies in PWA printers cannot be adequately corrected
Solution Approach 1:
The patent applies different NPAC vectors to different regions or patches on the calibration target, where each patch is optimized for specific ink combinations and sensitivity requirements. This local optimization allows each die to be calibrated with patches that are specifically tuned to its characteristics, improving color consistency across the entire printer width
Solution Approach 2:
The calibration target is divided into multiple patches, each with specific NPAC vectors corresponding to different ink combinations. This segmentation allows individual calibration of each die and ink channel, enabling precise correction of color variations across multiple dies without requiring a monolithic complex calibration system
3Measurement precision
If high sensitivity sensors are used to detect small color differences, then calibration accuracy improves, but the cost and complexity of the system increases
Solution Approach 1:
Instead of upgrading sensors, the patent changes the parameters of the calibration patches themselves by using NPAC vectors that produce larger, more detectable color changes in response to drop weight variations. This approach maintains measurement precision while avoiding the need for high sensitivity sensors
Solution Approach 2:
The patent converts the limitation of standard sensors (inability to detect small color differences) into a benefit by designing patches that amplify color changes. The NPAC vectors are selected to maximize the visible color difference for given drop weight variations, effectively compensating for sensor limitations without increasing system complexity
Data Source
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AI summary
A calibration target is disclosed. The calibration target is created such that a color patch is sensitive to drop weight changes.