Rotatable Press Down Mechanism for Image Forming Apparatus Curl Correction
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Solution Overview
Problem
Image forming apparatuses face issues with paper curling, leading to paper jams due to the press down unit's ineffective pressing point location, which moves away from the edge of the recording medium as the number of sheets increases, causing incomplete correction of curling.
Innovation Solution
An image forming apparatus with a rotatable press down mechanism having a rotation center positioned upstream of the discharge slot, ensuring the abutting surface consistently presses down the upstream end of the recording medium, maintaining effective curl correction regardless of the number of sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotation center of the press down unit is positioned to overlap the discharge tray in plan view, then the mechanism can press down recording media, but the pressing point moves away from the tail end of the recording medium as the number of recording media increases, reducing curl correction effectiveness
Solution Approach 1:
The rotation center is positioned asymmetrically upstream of the discharging slot rather than overlapping it, creating an offset configuration that ensures the pressing point remains consistently near the tail end of recording media regardless of stack height. This asymmetric positioning resolves the technical contradiction by maintaining pressing point stability while preserving the press down function.
Solution Approach 2:
The press down unit is positioned upstream of the discharging slot, performing the pressing action before the media exits the discharge area. This preliminary positioning ensures that the pressing point remains effective at the tail end of the media throughout the discharge process, preventing the pressing point from moving away as media is added to the stack.
2Reliability
If the press down unit is positioned to press down the tail end of the recording medium, then curl correction is effective, but the mechanism becomes more complex and may require additional power sources
Solution Approach 1:
The press down unit utilizes the weight of the recording media stack itself and the gravitational force on the rotatable arm to maintain pressing contact with the tail end of the media. The upstream rotation center positioning allows the media weight to naturally keep the abutting surface engaged with the media tail end, eliminating the need for additional motors or power sources while maintaining effective curl correction.
Data Source
AI summary
An image forming apparatus includes: a discharging slot provided for discharging a recording medium on which an image is formed; a discharge tray including a supporting surface supporting the recording medium discharged from the discharging slot; a discharge mechanism configured to discharge the recording medium to the discharge tray through the discharging slot; and a press down mechanism including an abutting surface which is provided for pressing down the upper surface of the recording medium supported by the supporting surface of the discharge tray. The press down mechanism is rotatable about a rotation center provided on the upstream of the discharging slot in a discharge direction in which the recording medium is discharged from the discharging slot, and the abutting surface contacts with the supporting surface when no recording medium is supported by the discharge tray.