Duplex Inkjet Drying Time Control for Overlap Areas
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Solution Overview
Problem
Inkjet printers face reduced printing throughput due to insufficient drying time calculations, leading to undried ink being discharged and causing sheet contamination when printing on both sides of a medium, as the existing techniques underestimate the drying time when ink-ejected areas overlap.
Innovation Solution
A droplet ejecting apparatus and computer-readable medium that determine the drying time by calculating the area drying time for overlap and non-overlap areas on a recording medium in duplex recording, adjusting the ink ejection volume based on ink penetration rate and conveying speed, ensuring accurate drying time determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drying time is calculated based on the total amount of ink ejected on both sides of a sheet, then the printing throughput is improved by reducing waiting time, but the drying time may be underestimated when ink-ejected areas overlap, causing sheets to be discharged before fully dry
Solution Approach 1:
The patent segments the recording medium into multiple areas based on ink ejection patterns: first-side ejection areas, second-side ejection areas, and overlap areas where ink from both sides contacts the same location. This segmentation allows differential drying time calculation, assigning longer drying times to overlap areas compared to non-overlap areas, thereby resolving the contradiction between maintaining high printing throughput and ensuring accurate drying time assessment.
2Reliability
If the waiting time is extended to ensure proper drying, then sheet contamination is prevented, but printing throughput decreases due to longer drying time
Solution Approach 1:
The patent applies local quality by assigning different drying time requirements to different areas of the recording medium. Overlap areas, where ink from both sides contacts the same location, are assigned longer drying times to prevent contamination, while non-overlap areas use shorter drying times. This localized approach ensures contamination prevention is applied only where necessary, maintaining printing throughput in areas where full drying is less critical.
3Device complexity
If the drying time is calculated using total ink amount without considering overlap, then the calculation is simple and fast, but it fails to account for the increased drying time required when ink-ejected areas overlap on both sides
Solution Approach 1:
The patent implements preliminary action by pre-defining area classification rules and drying time parameters before the actual printing process. The control unit is configured to automatically classify areas as overlap or non-overlap based on stored ejection pattern data, and to select appropriate drying times from pre-established tables. This preliminary setup enables accurate drying time determination without adding significant computational complexity during operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach accurately determines the drying time for duplex recording, preventing sheet contamination and maintaining printing efficiency by accounting for ink overlap and absorption rates, ensuring the ink is fully dry before discharge.
Implementation Method 1
a recording unit that ejects droplets
Implementation Method 2
adjusting the ink ejection volume based on ink penetration rate
Data Source
AI summary
In recording on a back side of a sheet in duplex recording, an overlapping pixel where both a pixel in back-side image data and a pixel opposed thereto in front-side image data has a gray level value larger than zero is retrieved from the front-side and back-side image data. A block area containing at least a predetermined number of overlapping pixels is extracted as an overlap area from block areas arranged in a matrix in the back-side image data. The area drying time in a block area other than the overlap area is determined from the volume of droplets to be ejected to the back side. The area drying time in the overlap area is determined from the total volume of droplets to be ejected to the front and back sides. The maximum area drying time is determined to be the drying time for the back side.