Ink-jet Printing Machine Sheet Deformation Control
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Solution Overview
Problem
Existing ink-jet printing machines face challenges in preventing damage to ink-jet heads due to printing sheet deformation, as conventional methods like optical sensors struggle with high-speed measurements and guide rollers have limitations in pressing deformation and can cause 'mist stain' issues.
Innovation Solution
An ink-jet printing machine with an orbital transfer belt, a sheet pressing roller, a detecting unit, and a guide roller, where the ratios of distances between these components are optimized to prevent deformation contact with the ink-jet heads, ensuring accurate detection and minimizing airflow disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guide roller is provided upstream of the ink-jet head to press the printing sheet, then the deformation of the printing sheet can be reduced, but the guide roller has a limit in keeping pressing the deformation and cannot handle all kinds of sheet deformations
Solution Approach 1:
The detecting unit is positioned to detect deformation before the printing sheet reaches the ink-jet head. When deformation is detected, the transfer belt speed is adjusted in advance to prevent contact between the deformed sheet and the ink-jet head, thereby preventing damage while adapting to various deformation types
Solution Approach 2:
The transfer belt speed is made variable and can be adjusted dynamically based on real-time deformation detection. This allows the system to adapt to different deformation conditions by changing the transfer speed accordingly, providing both protection and versatility
2Difficulty of detecting and measuring
If the optical sensor is used to detect printing sheet deformation, then the detection capability is provided, but the optical sensor has difficulty in measuring exact distance due to color influence and cannot keep up with high-speed printing
Solution Approach 1:
The optical sensor is replaced with a mechanical contact-type detecting unit that directly contacts the printing sheet to detect deformation. This mechanical detection method is not influenced by color and provides accurate distance measurement, while the high-speed capability is maintained through direct mechanical sensing rather than optical processing
3Reliability
If a steel plate is used to cover the transfer path to keep pressing the deformation, then the printing sheet deformation can be controlled, but the steel plate generates local airflow that disturbs ink flow and causes mist stain
Solution Approach 1:
The steel plate is removed from the transfer path. Instead, a guide roller is used to press the printing sheet, which does not generate the harmful local airflow that the steel plate would cause. This eliminates the mist stain problem while maintaining deformation control capability
Solution Approach 2:
The guide roller applies localized pressure to the printing sheet deformation area without creating widespread airflow disturbance. The pressing action is concentrated where needed, unlike the steel plate which creates broad area airflow disruption and mist stain
Data Source
AI summary
An ink-jet printing machine has: a transfer belt that transfers a printing sheet; a sheet feeding unit that feeds the printing sheet; an ink-jet head that performs ink ejection on the printing sheet; a SS roller that presses a central region of the printing sheet between the sheet feeding unit and the ink-jet head; a printing sheet sensor that detects the deformation of the printing sheet; and a guide roller that presses the printing sheet. The rate of a distance A between the SS roller and the printing sheet sensor to a distance B between the upper surface of a transfer belt and the lower end of the printing sheet sensor is approximately equal to the rate of a distance A′ between the guide roller and the ink-jet head to a distance B′ between the upper surface of the transfer belt and the lower end of the ink-jet head.