Inkjet Head Nozzle Switching for Density Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ink-jet printers face issues with image quality due to misalignment of nozzle rows, leading to local density changes and conspicuous differences in density between overlapping and non-overlapping ranges, causing degradation in print quality.
Innovation Solution
Implementing a liquid jetting apparatus with two head units where nozzles are arranged to overlap partially, using three or more switching positions within a narrower switching range that varies for each dot-row, ensuring ink is jetted from both nozzles in the overlapping range to distribute density uniformly and avoid conspicuous bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nozzles in overlapping range are used to increase productivity, then printing coverage is improved, but misalignment causes local density changes that degrade image quality
Solution Approach 1:
The patent applies local quality by differentiating nozzle selection strategies between overlapping and non-overlapping ranges. In the overlapping range, nozzles are selectively switched based on position to compensate for misalignment, while in the non-overlapping range, fixed nozzles are used. This localized adaptation resolves the contradiction by maintaining image quality in the overlapping region while preserving productivity benefits across the entire printing area.
Solution Approach 2:
The patent implements dynamics by making the nozzle selection dynamic rather than fixed. The control unit dynamically determines which nozzles to activate based on the superimposed image data and the specific position within the overlapping range. This dynamic adjustment allows the system to adapt to misalignment conditions in real-time, maintaining image quality while utilizing the productivity benefits of multiple head units.
2Manufacturing precision
If nozzle switching is implemented at a fixed predetermined position, then assembly errors are compensated, but a conspicuous density change appears at the switching position
Solution Approach 1:
The patent applies segmentation by dividing the overlapping range into multiple sections and using different switching positions for different dot rows. Instead of a single fixed switching position for all nozzles, the system segments the control strategy so that each dot row can have its own optimized switching position. This segmentation distributes the density changes across multiple locations rather than concentrating them at one conspicuous point.
Solution Approach 2:
The patent implements periodic action by alternating the switching positions for adjacent dot rows. The control unit periodically varies the switching position from one dot row to the next, creating a pattern that distributes density changes uniformly across the overlapping range. This periodic variation prevents any single location from having consistently high or low density, making the changes inconspicuous.
3Manufacturing precision
If the entire overlapping range is used for switching nozzles, then density uniformity is improved, but a band appears at the boundary with non-overlapping range
Solution Approach 1:
The patent applies local quality by creating a transition zone at the boundary between overlapping and non-overlapping ranges. In this transition zone, the nozzle switching is gradually reduced or modified compared to the interior of the overlapping range. This localized adjustment at the boundary prevents the abrupt density change that would otherwise create a visible band, while still maintaining density uniformity in the main overlapping region.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
There is provided a liquid jetting apparatus, including: a head unit and a controller. The controller is configured to: form a plurality of dot-rows by nozzles in a first range, and form the same dot-rows by nozzles in a second range; switch the nozzles jetting the liquid, between the nozzles in the first and second ranges, at the time of forming the dot-rows; narrow a switching range to be narrower than the first and second ranges; set the switching positions such that there are not less than three switching positions in the switching range; and set the switching range such that the switching range differs for the two dot-rows which are adjacent in the direction of intersection.