Correction Roller Protrusions for Skew Control and Ink Transfer Reduction
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Solution Overview
Problem
Ink jet printers face issues with print quality due to skewed medium transport and the risk of ink stains on correction rollers, leading to potential ink transfer to subsequent sheets during two-side printing.
Innovation Solution
A printing apparatus with a correction roller pair featuring protruded portions for point contact with the medium, a switchback mechanism for efficient sheet handling, and a cleaning member for maintaining roller cleanliness, reducing ink adhesion and transfer risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a correction roller pair is used to perform skew correction by causing firm contact with the medium, then skew correction accuracy is improved, but the risk of ink stain transfer to subsequent sheets increases
Solution Approach 1:
The correction roller is divided into multiple protruded portions (teeth) that contact the medium at discrete points rather than a continuous surface. This segmentation reduces the total contact area with the printed surface, minimizing ink adhesion while maintaining skew correction functionality through the distributed contact points.
Solution Approach 2:
The correction roller is designed with protruded portions that create localized point contact regions on the medium surface. This local quality approach concentrates the correction force at specific points while leaving the majority of the printed surface untouched, thereby reducing ink transfer risk while preserving the necessary skew correction capability.
2Object-generated harmful factors
If protruded portions are provided on the correction roller for point contact, then ink adhesion is reduced, but the complexity of the roller structure increases
Solution Approach 1:
The correction roller is segmented into multiple identical protruded portions (teeth) arranged around its circumference. This modular segmentation allows the complex contact surface to be constructed from repeated simple elements, making the structure easier to manufacture and maintain compared to a uniquely complex surface.
Solution Approach 2:
The roller structure parameters (number of teeth, tooth height, tooth spacing) can be adjusted to optimize the balance between ink adhesion reduction and structural complexity. By changing these parameters, the design can be tuned to achieve sufficient ink reduction with minimal increase in structural complexity.
3Measurement precision
If the correction roller actively rotates to transport the medium, then transport accuracy is improved, but the risk of ink transfer to the roller surface increases
Solution Approach 1:
The actively rotating correction roller features segmented protruded portions that intermittently contact the medium during rotation. This segmentation means that at any given moment, only discrete points are in contact, reducing the total ink adhesion time and area compared to a continuous surface roller, while the active rotation maintains transport accuracy.
Solution Approach 2:
The rotating correction roller with protruded portions creates a periodic contact pattern with the medium as it rotates. This periodic action reduces continuous ink adhesion exposure, allowing the roller to maintain transport function while minimizing the window of opportunity for ink transfer to the roller surface.
Data Source
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AI summary
A printing apparatus includes a printing unit that prints an image on a sheet by using ink, a feed path along which the sheet is transported toward the printing unit, a switchback mechanism that, when two sides of the sheet are to be printed, switches back the sheet of which one of the two sides has been printed and sends the sheet to the feed path, and a correction roller pair capable of correcting skew of the sheet by having firm contact with the sheet transported along the feed path. The correction roller pair includes a correction driving roller (61) and a correction driven roller that face each other and transports the sheet toward the printing unit as the correction driving roller (61) and the correction driven roller nip the sheet and rotate. The correction driving roller (61) has on its peripheral surface a plurality of protruded portions (77) capable of having point contact with the sheet and contacts the sheet from a side opposite, across the feed path, to a side on which the printing unit is provided.