Intermediate Conveyance Roller for Short Sheet Re-conveyance
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Solution Overview
Problem
In image forming apparatuses that perform duplex printing, the increased distance between the switchback roller and the return conveyor limits the shortest sheet length that can be re-conveyed, and the addition of an intermediate conveyance roller may cause the apparatus to enlarge and be degraded by heat from the fixer.
Innovation Solution
An intermediate conveyance roller is positioned between the switchback roller and the lowermost portion of the return conveyor, located at a height where it is less affected by the fixer's heat, without increasing the apparatus's size, and the conveyor system is designed to efficiently convey sheets through a chute unit with varying conveyance roller speeds and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If an intermediate conveyance roller is added between the switchback roller and the lowermost portion of the return conveyor, then the shortest sheet length that can be re-conveyed is decreased, but the overall size of the apparatus increases
Solution Approach 1:
The intermediate conveyance roller is positioned in the vertical dimension at a height intermediate between the fixer and the sheet cassette, rather than extending the apparatus in the horizontal dimension. This spatial arrangement allows the roller to be integrated within the existing vertical space of the apparatus, reducing the need to increase the overall footprint while still achieving the desired sheet length reduction capability.
2Length of moving object
If an intermediate conveyance roller is provided in the return passage, then the shortest sheet length is decreased, but the roller may be degraded by heat from the fixer
Solution Approach 1:
The intermediate conveyance roller is positioned at a specific vertical location in the return passage where the thermal environment is more favorable. By selecting a height intermediate between the fixer and the sheet cassette, the roller operates in a zone with reduced thermal exposure compared to positions closer to the fixer, thereby maintaining roller durability while still enabling short sheet conveyance.
3Volume of moving object
If the discharge roller is configured to function as both a discharge roller and a switchback roller, then the apparatus size is reduced, but the distance between the switchback roller and the return conveyor increases
Solution Approach 1:
The return passage is segmented into multiple sections with intermediate conveyance rollers positioned at different locations. This segmentation allows the sheet conveyance path to be divided into shorter segments, reducing the overall distance requirements between major components like the switchback roller and the return conveyor, thereby enabling compact apparatus design.
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 allows for a decrease in the shortest sheet length that can be re-conveyed while preventing the intermediate conveyance rollers from being degraded by heat, maintaining the apparatus's size and ensuring stable sheet conveyance.
Implementation Method 1
a fixer disposed above the sheet cassette and configured to thermally fix the image formed on the sheet
Implementation Method 2
an intermediate conveyance roller disposed in the return passage at a height level intermediate between the fixer and the sheet cassette
Data Source
AI summary
An image forming apparatus, including: a sheet cassette; an image former; a fixer; a discharge tray; a conveyor configured to convey a sheet along a conveyance passage; a return conveyor configured to convey the sheet from a branch position between the fixer and the discharge tray to a merge position between the sheet cassette and the image former along a return passage which is branched from the conveyance passage at the branch position, passes below the sheet cassette, and merges with the conveyance passage at the merge position; a switchback roller disposed between the branch position and the discharge tray in the conveyance passage and configured to convey the sheet to the discharge tray when it rotates forwardly and to the return passage when it rotates backwardly; and an intermediate conveyance roller disposed in the return passage at a height level intermediate between the fixer and the sheet cassette.