Printer Sheet Ejection Protrusions for Jam Prevention
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Solution Overview
Problem
Existing printers that eject sheets upward face issues with jamming due to uneven sheet holding forces, where fully cut sheets overlap and cause frictional jams, while partially cut sheets are not held securely, leading to breakage or uncertainty in sheet handling.
Innovation Solution
The printer incorporates first and second protrusions within the sheet ejection port, arranged in an undulating pattern to moderate the holding force, ensuring that fully cut sheets are securely held without causing jams and that partially cut sheets are conveyed without excessive force, using a combination of plate-shaped protrusions with varying heights and orientations to manage sheet curvature and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sheet holding force of the ribs is increased to securely hold fully cut sheets, then fully cut sheets are held reliably, but partially cut sheets experience breakage at the connected part causing sheet jams
Solution Approach 1:
The patent applies local quality by making the protrusions have different heights in different regions: higher protrusions at both end portions and lower protrusions at the central portion. This allows the holding force to be stronger at the ends (for fully cut sheets) and weaker at the center (for partially cut sheets with connected parts), thereby preventing sheet breakage while maintaining reliable holding.
2Ease of operation
If the number of ribs or their height is reduced to weaken holding force and prevent jam, then partially cut sheets are conveyed smoothly, but the holding function for fully cut sheets becomes uncertain
Solution Approach 1:
The patent maintains multiple protrusions across the sheet width but varies their heights locally. The higher protrusions at the ends provide strong holding for fully cut sheets, while the lower central protrusions allow smooth passage for partially cut sheets. This resolves the contradiction by preserving overall holding capability while creating local low-resistance zones.
3Device complexity
If uniform protrusions are used across the sheet width, then the structure is simple, but it cannot simultaneously handle both fully cut and partially cut sheets without jam or breakage
Solution Approach 1:
The patent maintains relative structural simplicity by using multiple identical protrusion units, but introduces local differentiation through varying heights. This allows the system to handle both fully cut and partially cut sheets reliably while keeping the overall structure manageable and manufacturable.
Solution Approach 2:
The patent segments the protrusion structure into multiple independent units across the sheet width, with different height characteristics for different regions. This segmentation allows each region to be optimized for its specific function (holding vs. smooth passage) while maintaining overall system coherence.
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 configuration effectively prevents jams in both full and partial cut operations by maintaining a balanced holding force, ensuring smooth sheet ejection and stacking without breakage or overlap issues, enhancing the printer's reliability and functionality.
Implementation Method 1
first protrusions protruding from an inner periphery of the sheet ejection port and provided at a plurality of locations along a width direction of the sheet to face a first surface which is a surface of the sheet on a side to be printed, and second protrusions protruding from an inner periphery of the sheet ejection port, provided at a plurality of locations along the width direction of the sheet at positions deviated from the first protrusions in the sheet width direction to face a second surface which is a back surface of the first surface of the sheet, and configured to bend the sheet in an undulating shape in the width direction between the first protrusions and the second protrusions
Implementation Method 2
the cut sheet held by the ribs overlaps with the sheet to be conveyed next, and thus, a frictional force acts between the sheets. As a result, the cut sheet also moves between the ribs together with the next sheet
Data Source
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AI summary
A housing is provided with a sheet ejection port for discharging upward a sheet that has passed through a printing unit. A cutting unit is arranged between the printing unit and the sheet ejection port and cuts the sheet by either a method of cutting the sheet in the entire width direction or a method of leaving the central portion of the sheet in the width direction. First protrusions and second protrusions protruding from the inner periphery of the sheet ejection port are provided at a plurality of locations along the width direction of the sheet. The first protrusion faces a first surface of the sheet and the second protrusion faces a second surface, which is the back surface of the first surface of the sheet. The first protrusion and the second protrusion are provided at positions deviated from each other in the sheet width direction and bend the sheet in an undulating shape in the width direction therebetween. Further, a protrusion height of at least either the first protrusions or the second protrusions in the central portion in the width direction of the sheet is lower than protrusion heights of the first protrusions and the second protrusions in other regions.