Full-Line Printhead Ink Landing Position Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Printing quality is degraded due to errors in the mounting position of printheads or relative positions of multiple printheads in full-line printheads, leading to ink landing position shifts, and existing methods fail to accurately read test patterns when printing medium conveyance shifts occur, resulting in measurement errors.
Innovation Solution
A printing apparatus with a full-line printhead that forms and reads patterns on the printing medium using a CCD line sensor, calculating and correcting the ink landing position shift by arranging multiple chips with nozzle arrays and using a pattern forming control unit, reading unit, calculation unit, and correction unit to adjust nozzle discharge based on the positional relationship between patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test pattern is read using a CCD line sensor while conveying the printing medium, then the ink landing position can be corrected, but measurement error increases when printing medium conveyance shift occurs
Solution Approach 1:
The patent uses pattern matching between a reference pattern and a test pattern to create a virtual copy of the ideal position relationship. By comparing the relative positions of corresponding features in both patterns, the system can determine ink landing position shifts without being affected by overall conveyance shifts, thus maintaining measurement accuracy and reliability
Solution Approach 2:
The patent changes the measurement approach from absolute position measurement to relative position measurement. Instead of measuring the absolute position of the test pattern, it measures the relative position between the test pattern and reference pattern, making the measurement invariant to conveyance shifts and improving both accuracy and reliability
2Loss of time
If the same pattern is repeatedly printed and read for adjustment, then adjustment time is shortened and test pattern length is decreased, but measurement error increases when conveyance shift occurs
Solution Approach 1:
The patent creates a reference pattern that serves as a stable reference copy. By comparing the test pattern against this reference using pattern matching, the system can perform rapid adjustments without sacrificing measurement accuracy, even when conveyance shifts occur during reading
3Productivity
If a full-line printhead with multiple chips is used to print entire width, then printing efficiency is improved, but ink landing position shift increases due to mounting position errors
Solution Approach 1:
The patent implements a feedback mechanism where the actual ink landing positions are measured using the CCD line sensor and pattern matching, and the measured deviations are used to correct the printing data for each nozzle array. This closed-loop control compensates for mounting position errors in multi-chip full-line printheads, maintaining manufacturing precision while preserving high productivity
Solution Approach 2:
The patent applies individual correction values to each nozzle array based on its specific measured deviations. Instead of applying a uniform correction, the system tailors the correction to each local region (nozzle array), accounting for variations in mounting position errors across different chips and nozzle arrays, thus improving overall manufacturing precision
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
This solution reduces measurement errors even when printing medium conveyance shifts occur, ensuring accurate ink placement and improved printing quality by correcting the ink landing position based on calculated shift amounts.
Implementation Method 1
a reading unit configured to read the plurality of first patterns from the printing medium during conveyance using a sensor
Data Source
AI summary
A printing apparatus includes a full-line printhead in which a plurality of chips, on each of which a plurality of nozzle arrays are juxtaposed, are arranged in the nozzle arrayed direction, and which prints by the entire width of a printing medium using a plurality of nozzles arranged on the plurality of chips. The printing apparatus discharges ink from a predetermined number of successive nozzles on each nozzle array of each chip toward a printing medium during conveyance, thereby forming a plurality of first patterns corresponding to at least one nozzle array of each chip on the printing medium in the nozzle arrayed direction, reads the plurality of first patterns from the printing medium during conveyance using a sensor, calculates the shift amount of an ink attached position based on the plurality of read first patterns and corrects the attached position of ink based on the shift amount.