Inkjet Printer Drying Unit Reverse Conveyance Control
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Solution Overview
Problem
In inkjet printing systems, when a recording medium is rewound in reverse direction, the heat transfer from the drying unit can cause ink evaporation and condensation on the nozzle surface, leading to reduced ejection accuracy and image quality, especially for high-density prints.
Innovation Solution
A control mechanism is implemented to reduce the heat transfer from the drying unit during reverse conveyance by adjusting the air volume or temperature, ensuring that the recording paper is not reheated to the same extent as during forward conveyance, thereby preventing dew condensation on the nozzle surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the recording medium is conveyed in the reverse direction through the drying unit, then the drying efficiency is improved and drying time is shortened, but the heat transfer from the drying unit causes ink evaporation and condensation on the nozzle surface, reducing ejection accuracy and image quality
Solution Approach 1:
The patent applies dynamics by making the drying unit's operation conditional and variable. The drying unit is activated only during forward conveyance and deactivated during reverse conveyance, allowing the system to adapt its drying function based on the conveyance direction. This dynamic control resolves the contradiction by enabling high drying efficiency during forward passes while preventing harmful heat transfer and condensation during reverse passes when the print head is nearby.
Solution Approach 2:
The patent changes the operational parameters of the drying unit based on conveyance direction. By switching the drying unit's activation state (on/off) depending on whether the conveyance is in the forward or reverse direction, the system optimizes drying efficiency during forward passes while avoiding overheating and condensation issues during reverse passes. This parameter change approach allows the same drying unit to serve different functions under different operating conditions.
2Duration of action of stationary object
If the recording medium is conveyed in the reverse direction, then the drying unit can process the medium more times, but the volatile components of warmed ink evaporate and condense on the head nozzle surface, adversely affecting image quality
Solution Approach 1:
The patent applies preliminary anti-action by deactivating the drying unit before reverse conveyance begins. This preventive measure stops the drying unit from operating when the recording medium is being conveyed in reverse direction, thereby preventing the evaporation of volatile ink components and their subsequent condensation on the nozzle surface. The control unit anticipates the potential harm and takes action in advance by controlling the drying unit's operation based on conveyance direction.
3Speed
If the drying unit operates at high heat transfer during reverse conveyance, then drying speed is improved, but the recording medium reaches the ink ejection head position while still warm, causing ink evaporation and condensation
Solution Approach 1:
The patent applies dynamics by making the drying unit's operation conditional on conveyance direction. The drying unit operates at high heat transfer during forward conveyance to achieve fast drying, but is deactivated during reverse conveyance to prevent condensation on the nozzle. This dynamic control strategy allows the system to maximize drying speed when beneficial while maintaining image quality consistency by preventing harmful condensation during reverse passes.
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 maintains image quality by preventing nozzle surface reheating and subsequent dew condensation, ensuring consistent ejection accuracy during both forward and reverse conveyance operations.
Implementation Method 1
a drying unit provided downstream of the printing unit in the first direction and configured to dry the print medium on which an image is printed
Implementation Method 2
a heat transfer amount from the drying unit to the print medium
Data Source
AI summary
A printing apparatus includes a conveying unit configured to convey a print medium with respect to a printing unit configured to eject liquid, a drying unit provided downstream of the printing unit in a first direction and configured to dry the print medium, and a control unit configured to perform control such that, in a case where the print medium is conveyed in a second direction opposite to the first direction after the image on the print medium is passed through the drying unit by conveying in the first direction, a heat transfer amount from the drying unit to the print medium is smaller than a heat transfer amount from the drying unit to the print medium in a case where the print medium is conveyed in the first direction.