Inkjet Head Gap Calibration for Accurate Ink Landing Position
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Solution Overview
Problem
Conventional methods for adjusting inkjet printers require significant effort and time, and are prone to variations due to operator differences, leading to inconsistent printing quality.
Innovation Solution
An adjustment method for inkjet printers that involves printing a test pattern with varying inkjet head heights, analyzing the resulting ink landing positions, and adjusting the drive signal voltage based on detected positional shifts to ensure accurate ink ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional adjustment methods are used for each nozzle of multiple inkjet heads, then measurement precision of ink ejection can be achieved, but adjustment time and operational complexity increase significantly
Solution Approach 1:
The patent segments the adjustment process into two levels: (1) group-level adjustment where a test pattern is printed and analyzed to determine common offset values for all nozzles in an inkjet head, and (2) individual nozzle adjustment using the pre-calculated offset values. This segmentation reduces the adjustment time from adjusting each nozzle separately to adjusting the entire inkjet head as a group first, then making individual corrections only where needed.
Solution Approach 2:
The patent performs preliminary action by pre-calculating offset values for all nozzles in an inkjet head based on a test pattern analysis before actual printing. The offset values are determined in advance by analyzing the positions of ink dots printed at different head heights, and these pre-calculated values are then used to adjust all nozzles systematically, avoiding the need for time-consuming individual nozzle adjustments during normal operation.
2Measurement precision
If conventional adjustment methods are used for each nozzle of multiple inkjet heads, then measurement precision of ink ejection can be achieved, but operational complexity and variability due to operator differences increase
Solution Approach 1:
The patent implements self-service by enabling the inkjet head to print its own test pattern and by providing automated analysis of the printed pattern to determine offset values. The system uses the printed test pattern itself as the measurement target, eliminating the need for external measurement devices or complex manual procedures. This self-service approach reduces operational complexity and minimizes variability caused by different operators.
Solution Approach 2:
The patent employs feedback by analyzing the actual printed test pattern to determine offset values for nozzle adjustment. The system prints a test pattern with known geometry, measures the actual positions of ink dots, calculates the deviations (offsets) from expected positions, and uses these measured offsets to adjust the nozzle ejection timing or voltage. This closed-loop feedback ensures consistent, objective adjustment that is not subject to operator variability.
3Measurement precision
If head gap is varied in multiple levels for pattern printing, then measurement precision of ink landing position can be improved, but printing complexity increases
Solution Approach 1:
The patent applies dynamics by varying the head gap (distance between inkjet head and medium) across multiple levels during test pattern printing. Instead of printing at a fixed head gap, the system dynamically adjusts the head gap to multiple different heights, printing test patterns at each level. This dynamic variation in head gap allows measurement of ink landing position as a function of ejection velocity, improving measurement precision while the systematic approach to varying gaps keeps the process manageable.
Data Source
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Figure 2(a)~2(b)
Figure 3
AI summary
Adjustment to an inkjet printer is performed easily and appropriately. An adjustment method for performing adjustment to a printing apparatus 12 which is an inkjet printer includes: a pattern printing step of causing the printing apparatus 12 to print a test pattern; an analysis step of analyzing a result of reading the test pattern; and an adjustment step of performing an adjustment by which a result of the analysis in the analysis step is reflected in an operation of the printing apparatus 12. The printing apparatus 12 includes an inkjet head, a main scanning drive unit 112, and a head position adjustment unit 118. In the pattern printing step, a head gap is varied in the plurality of levels, and the printing apparatus 12 is caused to print the test pattern. In the analysis step, a difference in an ink landing position in a main scanning direction that occurs due to a difference in the head gap is detected based on the test pattern. In the adjustment step, the adjustment is performed based on the difference in the ink landing position.