Inkjet Print Head Dew Control via Conveyor Suction Airflow
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Solution Overview
Problem
Inkjet printing systems face issues with dew formation on print heads due to saturated air humidity, leading to image defects, which requires additional sensors and air conditioning units for control.
Innovation Solution
The method involves controlling the sheet-to-sheet distance on an endless conveyor to create a suction airflow through uncovered perforations, reducing relative humidity and preventing dew formation by increasing the evaporation rate, without the need for additional air conditioning units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensors and air conditioning units are added to prevent dew formation, then dew formation on print heads is prevented, but device complexity increases
Solution Approach 1:
The system uses the existing suction device and uncovered perforations to create airflow that prevents dew formation. The suction device, originally intended for sheet handling, is leveraged to serve the additional function of dew prevention by creating airflow through the uncovered perforations in the print region, eliminating the need for separate air conditioning units or sensors.
Solution Approach 2:
The suction device is made multi-functional by using it both for sheet handling and for dew formation control. The uncovered perforations serve dual purposes: allowing suction force to hold sheets on the support surface while also enabling airflow to pass through and prevent dew formation on print heads.
2Reliability
If sheet-to-sheet distance is increased to prevent dew formation, then dew formation on print heads is reduced, but productivity decreases
Solution Approach 1:
The system uses pneumatic principles by utilizing the suction force created through the uncovered perforations to generate airflow in the print region. This airflow actively removes moisture and prevents dew formation on the print heads, allowing the system to maintain optimal sheet-to-sheet distances for high productivity while still preventing dew formation through the pneumatic airflow mechanism.
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 effectively controls dew formation on print heads, maintaining productivity while reducing the risk of image defects and eliminating the need for additional air conditioning units.
Implementation Method 1
A suction device is arranged comprising a vacuum chamber arranged for applying the suction force to the perforations of the support surface in order to attract each of the plurality of sheets on the support surface
Implementation Method 2
When droplets of an aqueous ink are applied on the sheet evaporation of the water component may occur, thereby increasing the humidity of the air present in a print region between the print head assembly and the support surface
Implementation Method 3
The suction force provides an airflow through uncovered perforations present in the sheet-to-sheet distance in a print region between the print head assembly and the support surface
Data Source
Figure 1
Figure 2A~2C
Figure 3A~4
AI summary
The present invention relates to a method for printing on a plurality of sheets (20, 22). The method comprising the steps of: arranging the plurality of sheets on a support surface (14) of an endless conveyor, the plurality of sheets including a first sheet and a second sheet being arranged at a sheet-to-sheet distance (SI) between one another; advancing the plurality of sheets on the support surface in a conveying direction (T) along a print head assembly (12a-12d) for applying droplets of ink on the sheets; providing a suction force through perforations arranged in the support surface for holding the plurality of sheets on the support surface, wherein the suction force provides an air flow through uncovered perforations present in the sheet-to-sheet distance in a print region between the print head assembly and the support surface; and forming an image by the print head assembly on each of the plurality of sheets supported on the support surface of the conveyor by applying droplets of ink. The method further comprises the step of controlling the sheet-to-sheet distance in response to a dew formation attribute for indicating dew formation on the print head assembly.