Tray Cover Inclination for Sheet Jamming Prevention
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Solution Overview
Problem
In existing image forming apparatuses, when the tray cover is in the covering position, sheets ejected from the nip portion of the ejection roller can get jammed due to contact with the lower surface of the tray cover, leading to operational inefficiencies.
Innovation Solution
The design includes a tray cover with an upper surface facing upward, allowing the leading end of the sheet to pass over it, reducing jamming by eliminating contact with the lower surface of the tray cover, and the tray cover is inclined downward to prevent dust accumulation and improve aesthetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the tray cover is positioned to cover the ejection tray completely, then the aesthetic appearance and dust protection are improved, but sheet jamming occurs due to contact between the ejected sheet and the tray cover
Solution Approach 1:
The tray cover is designed with an inclined upper surface that slopes downward in the sheet ejection direction. This dimensional change in the surface geometry allows sheets to glide smoothly over the cover without contact, eliminating jamming while maintaining the covering position for dust protection and aesthetic appearance.
2Volume of moving object
If the end portion of the tray cover is located above the nip portion of the ejection roller, then the compact design is achieved, but sheet jamming occurs due to contact with the lower surface of the tray cover
Solution Approach 1:
The tray cover features a curved inclined upper surface that slopes downward toward the sheet ejection direction. This curvature allows sheets to follow a smooth trajectory over the cover without abrupt contacts, enabling compact positioning while maintaining smooth sheet ejection.
3Device complexity
If the tray cover is made horizontal, then the structural simplicity is maintained, but dust accumulates on the upper surface
Solution Approach 1:
The tray cover upper surface is designed with an inclination angle rather than being horizontal. This dimensional change in surface orientation causes dust and debris to slide off the surface due to gravity, preventing accumulation while adding only minimal structural complexity.
Data Source
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AI summary
An image forming apparatus (1) includes an ejection tray (9) including a support portion (94a), a plurality of ejection rollers (8) having a nip portion, and a tray cover (10) having a first surface and a second surface and being configured to move between an extended position where the first surface faces upward and a covering position where the tray cover is supported by the support portion to cover an upper surface of the ejection tray and the second surface faces upward. When the tray cover is in the covering position, an upstream end portion of the second surface of the tray cover in a sheet ejection direction is disposed in a position closer to the nip portion than the upper surface of the ejection tray and lower than the nip portion such that a leading end of the recording sheet ejected from the nip portion passes on or over the second surface.