Inkjet Print Alignment Using Cell Keys for Thermal Drift Compensation
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Solution Overview
Problem
Inkjet printing technologies face challenges in maintaining precise alignment due to thermal drift of measuring instruments and changes in the position of the inkjet head over time, especially in high-resolution applications, leading to errors in discharging droplets at the correct pixel positions.
Innovation Solution
An aligning method for inkjet printing apparatuses that calculates the coordinates of cell and global keys on a glass substrate, derives offset correction values, and adjusts the printing start position to compensate for thermal changes and manufacturing errors, using a multi-head module with cameras and a printing position setting controller to ensure accurate droplet placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-head module with a plurality of inkjet heads is used to improve productivity, then mass production capability is improved, but maintaining precise alignment of nozzle positions with pixel positions becomes more difficult due to thermal drift and position changes over time
Solution Approach 1:
The system performs preliminary measurement of alignment key positions on the substrate before printing begins. These measured positions are stored and used as a reference basis for subsequent alignment corrections, allowing the system to pre-compensate for thermal drift and position changes that occur during the printing process
Solution Approach 2:
The system continuously monitors the positions of alignment keys on the substrate and compares them against the stored reference positions. Based on the detected deviations caused by thermal drift or head position changes, the system dynamically adjusts the printing coordinates to maintain precise alignment between nozzles and pixel positions throughout the printing process
2Manufacturing precision
If high-resolution printing is performed to improve image quality, then pixel definition is improved, but the tolerance for alignment errors decreases, making precise positioning more critical and difficult to maintain
Solution Approach 1:
The system establishes a reference coordinate system by measuring alignment keys before high-resolution printing begins. This preliminary measurement creates a baseline that accounts for the specific substrate position and thermal conditions at the start of printing
Solution Approach 2:
During high-resolution printing, the system continuously detects changes in alignment key positions and applies real-time coordinate corrections. This feedback mechanism ensures that even as thermal conditions change or the print head moves, the alignment precision required for high-resolution pixel definition is maintained throughout the entire printing process
Data Source
AI summary
An aligning method of an inkjet printing apparatus that prints a glass substrate with a plurality of cells arranged in a matrix form includes a first global key formed at a first position, and a plurality of cell keys formed around each of the plurality of cells. The aligning method further includes calculating the coordinates of each of the plurality of cell keys with the first global key as a reference based on the measurements of the plurality of cell keys and the first global key and reflecting the coordinates of the calculated cell key in the design pattern image to generate a corrected pattern image.