Dual Sheet Feeding Tray with Backward-Feed Prevention
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Solution Overview
Problem
Conventional image forming apparatuses face issues with paper jams and incorrect sheet feeding due to the integration of sheet feeding and discharge trays, leading to potential contact between stacked sheets and printed sheets, which can result in misfeeding and hinder image formation.
Innovation Solution
The design incorporates a dual-tray system where a first sheet feeding tray stores standard-sized sheets and a second, smaller tray serves both as a feeder and discharge tray, equipped with side guides and a plate part with a backward-feed prevention mechanism to prevent printed sheets from being re-fed into the print area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single tray is used for both sheet feeding and discharge, then the device size is reduced, but printed sheets may contact stacked sheets causing paper jams and misfeeding
Solution Approach 1:
The single tray is segmented into two functional zones: a first sheet feeding area for storing blank sheets and a second sheet discharge area for receiving printed sheets. The discharge area is further divided into a discharge receiving portion and a stacked sheet storage portion, creating spatial separation that prevents printed sheets from contacting blank sheets and causing misfeeding or paper jams.
Solution Approach 2:
A guide wall is introduced as an intermediary structure between the discharge receiving portion and the stacked sheet storage portion. This guide wall physically separates the two areas, guiding discharged sheets to the storage portion while preventing them from contacting blank sheets in the feeding area, thus resolving the contradiction between space efficiency and feeding reliability.
2Productivity
If sheets are stacked in the discharge tray, then discharge capacity is improved, but printed sheets may be wrongly fed to the print part again
Solution Approach 1:
The discharge tray is segmented into a discharge receiving portion for temporarily holding freshly printed sheets and a stacked sheet storage portion for storing discharged sheets. This segmentation ensures that stacked sheets are spatially separated from the feeding path, preventing them from being wrongly fed back to the print part while maintaining high discharge capacity.
Solution Approach 2:
A guide wall acts as an intermediary structure that directs discharged sheets to the stacked sheet storage portion and prevents them from entering the feeding path. This ensures that even when sheets are stacked, they cannot be mistakenly fed to the print part again, maintaining printing accuracy while improving discharge capacity.
3Manufacturing precision
If side guides are added to guide sheets, then feeding accuracy is improved, but device complexity increases
Solution Approach 1:
The guide wall serves multiple functions simultaneously: it guides discharged sheets to the storage portion, prevents printed sheets from contacting blank sheets, and defines the boundary between the discharge receiving portion and stacked sheet storage portion. By combining multiple functions into a single structure, feeding accuracy is improved without significantly increasing device complexity.
Solution Approach 2:
The guide wall is designed as a multi-functional component that performs guidance, separation, and boundary definition functions. This universal structure improves feeding accuracy while minimizing the increase in device complexity by avoiding the need for separate components for each function.
Data Source
AI summary
An image forming apparatus including: a print part; a feeding part; a first sheet feeding tray; and a second sheet feeding tray. The first sheet feeding tray stores a sheet of a first size therein, the feeding part feeding the sheet of the first size from the first sheet feeding tray to the print part in a sheet feeding direction. The second sheet feeding tray is mounted on the first sheet feeding tray and stores a sheet of a second size smaller than the first size therein, the feeding part feeding the sheet of the second size from the second sheet feeding tray to the print part in the sheet feeding direction, the second sheet feeding tray receiving a sheet printed by the print part and discharged in a direction opposite to the sheet feeding direction. The second sheet feeding tray has a pair of side guides which are provided in parallel to the sheet feeding direction and which contact against side ends of the sheet of the second side to guide the sheet of the second side to the print part. At least one of the pair of side guides is provided with a plate part which extends from an upper edge of the side guide to the other side guide and which receives the printed sheet thereon. The plate part has a backward-feed prevention part which prevents the printed sheet from being fed to the print part again.