Printing Apparatus Scan Control for Image Uniformity and Throughput
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Solution Overview
Problem
In multipass printing, stoppages during the printing process can lead to unevenness in the printed image due to changes in color and gloss, and existing techniques require additional scans to complete multipass printing before a stoppage, resulting in decreased throughput.
Innovation Solution
A printing apparatus with a control unit that manages the printing unit and conveyance unit to perform a first scan before a stoppage and a second scan after a predetermined time, where the first scan does not print on the region yet to be printed and the second scan completes the printing of that region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional scans are performed to complete multipass printing before a stoppage, then image quality uniformity is improved, but throughput decreases
Solution Approach 1:
The patent applies preliminary action by performing a first scan before the stoppage to print on regions that will not be printed again after the stoppage. This prepares the printing process in advance so that when the stoppage occurs, the minimal necessary printing is done beforehand, and the remaining printing is efficiently completed after resumption with a single second scan, avoiding the need for multiple additional scans and thus maintaining throughput while ensuring image quality uniformity.
2Ease of manufacture
If printing is stopped for a predetermined time, then maintenance operations (wiping, temperature management) can be performed, but unevenness appears in the printed image
Solution Approach 1:
The patent segments the printing process into three distinct phases: (1) first scan before stoppage that prints only on regions not to be printed again, (2) stoppage period for maintenance operations, and (3) second scan after resumption that completes printing on remaining regions. This segmentation allows maintenance operations to be performed during the stoppage while minimizing image quality unevenness by carefully controlling which regions are printed in each phase.
3Manufacturing precision
If the printing element array is scanned with no printing on yet-to-be-printed regions, then image quality unevenness is reduced, but the number of scans increases
Solution Approach 1:
The patent maintains continuity of useful action by ensuring that the first scan before stoppage and the second scan after resumption together cover all necessary printing regions without gaps or redundant scanning. The first scan prints on regions that will not be printed again, and the second scan completes printing on remaining regions, ensuring continuous and efficient use of the printing process while minimizing the number of additional scans needed.
Data Source
AI summary
In a case of inserting a stopping operation of causing a printing unit to perform no scan for a predetermined time or longer after starting printing of an image onto a print medium, a control unit controls the printing unit and a conveyance unit so as to perform a first scan in at least one scan before the stopping operation and a second scan in at least one scan resumed after an elapse of a predetermined time since the stoppage, the first scan being a scan in which the printing element array is scanned with no printing over a printing region yet to be printed, the second scan being a scan in which remaining part of the printing of the printing region not printed in the first scan is performed.