Dual-Printhead Nozzle Layout for Single-Pass Edge Sharpness
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Solution Overview
Problem
Existing printing technologies struggle to achieve homogeneous print results with high quality, good edge sharpness, and short cycle times, particularly in single-pass and multi-pass methods, due to limitations in printhead architecture and substrate movement.
Innovation Solution
A printing unit with two printheads arranged one behind the other, each with two rows of nozzles transverse to the substrate direction, offset and/or with reversed color sequences, simulating dual-pass printing in a single pass, using two colors per printhead to achieve maximum resolution and high print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single-pass printing method is used, then printing speed is improved, but print quality and edge sharpness deteriorate
Solution Approach 1:
The printhead is segmented into multiple nozzle rows (first row, second row, third row, fourth row) arranged in the transverse direction, with each row dedicated to specific colors. This segmentation allows simultaneous printing of multiple colors at high resolution without requiring multiple passes, thereby maintaining both high printing speed and good edge sharpness.
2Manufacturing precision
If multi-pass printing method is used, then print quality is improved, but cycle time increases
Solution Approach 1:
Multiple nozzle rows that would traditionally require separate printing passes are merged into a single printhead assembly. The first and second nozzle rows print one color while the third and fourth nozzle rows print another color simultaneously, combining multiple pass operations into one pass and eliminating the time loss associated with back-and-forth substrate movement.
Solution Approach 2:
All necessary nozzle rows with different color configurations are pre-installed in the printhead before printing begins. This preliminary arrangement of multiple color-capable nozzle rows eliminates the need for mechanical offset adjustments and repositioning between passes, thereby reducing cycle time while maintaining print quality.
3Device complexity
If two colors per printhead are used, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
Different nozzle rows within the same printhead are assigned different local qualities (colors). The first nozzle row is dedicated to a first color, the second nozzle row to a second color, and so on. This local differentiation allows the printhead to maintain high resolution for each color while printing multiple colors simultaneously, avoiding the need for mechanical offsets that would compromise precision.
Data Source
Figure 1~2b
Figure 2c~2d
Figure 3a~3b
AI summary
The invention relates to a printing unit (1) and a method for printing on a substrate (12). The printing unit (1) for printing on a substrate (12) comprises two printheads (2a, 2b) arranged one behind the other in the direction of travel of the substrate (12) and two pinning units (3a, 3b), wherein each printhead (2a, 2b) has one or more print chips (4) each with two rows of nozzles (5a, 5b, 5e, 5f) arranged transversely to the direction of travel of the substrate (12), wherein each row of nozzles (5a, 5b, 5e, 5f) has two or more nozzles (6).The two nozzle rows (5a, 5b, 5e, 5f) in each of the two printheads (2a, 2b) have a first color in one of the two nozzle rows (5a, 5e) and a second color, different from the first color, in a second of the two nozzle rows (5b, 5f), and either the color sequence of the first and second color in the two nozzle rows (5a, 5b, 5e, 5f) between the two printheads (2a, 2b) is identical and the two printheads (2a, 2b) further have a mechanical offset (7) from each other which corresponds to half the distance between two adjacent nozzles (6) of the two or more nozzles (6), or the color sequence of the first and second color in the two nozzle rows (5a, 5b, 5e, 5f) between the two printheads (2a, 2b) is reversed.