Inkjet Printer Roller Off-Center Correction via Test Pattern Analysis
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Solution Overview
Problem
Inkjet printing apparatuses face challenges in reducing ink landing position deviation due to roller off-centering, which requires costly measurements and often results in unnecessary replacement of parts, leading to waste.
Innovation Solution
An inkjet printing apparatus that includes an inkjet head, a roller, an encoder, and a controller capable of obtaining off-center information by printing a test pattern and calculating the off-center information based on dot positions, allowing for correction of ink ejection timing without the need for large measurement units or unitizing the encoder and roller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the encoder or roller is replaced, then the ink landing position deviation can be corrected, but a large and high-cost measurement unit needs to be brought to the user site
Solution Approach 1:
The patent uses the inkjet head itself to print a test pattern that copies the roller's rotational characteristics onto the print medium. By analyzing the printed dot positions, the system creates a digital representation of the roller profile without needing external measurement equipment. This copying approach replaces complex physical measurement devices with a simple printing and analysis process.
Solution Approach 2:
The inkjet printing apparatus performs its own self-diagnosis and calibration by using its inkjet head to print test patterns and analyze the results. The system measures its own roller characteristics through the printed output, eliminating the need for external measurement devices to be brought to the user site.
2Loss of time
If the encoder and roller are unitized, then the roller profile data can be obtained during manufacturing, but parts are wasted when only the roller needs replacement
Solution Approach 1:
The patent separates the roller and encoder into independent replaceable components while maintaining the ability to measure and store roller profile data independently. This segmentation allows the roller to be replaced without the encoder, preventing unnecessary part wastage while still enabling quick measurement and correction of roller issues.
Solution Approach 2:
The system performs preliminary measurement of the roller profile when the roller is first installed or replaced, storing the data for future corrections. This preliminary action ensures that when the roller is replaced, the profile data is already available in the controller, eliminating the need to bring measurement equipment to the user site while allowing selective replacement of only the roller.
3Extent of automation
If the ink ejection timing is controlled based on encoder pulse signal, then the printing operation is automated, but ink landing position deviation occurs when roller is off-centered
Solution Approach 1:
The system uses feedback from the printed test pattern to detect roller off-centering and automatically adjusts the ink ejection timing compensation values. By printing test patterns, measuring dot positions, and using this information to correct timing errors, the system maintains both automation and precision despite roller imperfections.
Solution Approach 2:
The patent dynamically changes the ink ejection timing parameters based on the measured roller profile. The controller adjusts the ejection timing compensation values according to the specific off-centering characteristics detected from the test pattern, allowing the automated system to adapt to roller variations and maintain precise ink landing positions.
Data Source
AI summary
An inkjet printing apparatus includes: a roller configured to rotate in synchronization with the print medium being conveyed; an encoder configured to output a pulse signal depending on a rotation angle of the roller; and a controller. The controller is configured to: perform an off-center information obtaining processing of driving the inkjet head to print a test pattern including dots arranged in a conveyance direction of the print medium and calculating an off-center information of the roller based on positions of the dots in the printed test pattern; and in the printing operation, correct the ejection timing of the ink by the inkjet head determined based on the pulse signal outputted from the encoder, based on the off-center information calculated in the off-center information obtaining processing.