Sheet Ejection Protrusion Member Reciprocation for Drooping Prevention
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Solution Overview
Problem
Existing sheet ejection devices in image forming systems face challenges in efficiently stacking sheets while preventing drooping of end portions, particularly in systems where the sheet ejection device is installed around the ejection port of the image forming apparatus.
Innovation Solution
A sheet ejection device with a protrusion member that can reciprocate between a protrusion position and a retraction position, guided by a rack and pinion mechanism, which temporarily supports the sheets to prevent drooping and ensures proper stacking on the tray.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sheets are stacked directly on the stacking tray without temporary support, then the stacking process is simple, but the end portions of sheets droop due to gravity
Solution Approach 1:
The protrusion member is positioned in advance to support the sheet end portions before they are fully deposited on the stacking tray. This preliminary support prevents drooping during the stacking process, and the member retracts after serving its purpose, maintaining simplicity while ensuring proper sheet shape.
2Shape
If a fixed protrusion member is used to support sheets, then sheet drooping is prevented, but the device complexity increases due to additional movement mechanisms
Solution Approach 1:
The protrusion member transitions from a fixed structure to a dynamic one that can reciprocate between protrusion and retraction positions. This dynamic capability allows the member to provide support only when needed, reducing interference with sheet ejection while maintaining drooping prevention functionality.
Solution Approach 2:
The protrusion member operates periodically, protruding to support sheets during stacking and retracting to avoid interference during sheet ejection. This periodic reciprocation is controlled by a rack and pinion mechanism that converts rotational motion into linear reciprocating motion of the protrusion member.
3Manufacturing precision
If the pinion gear continuously meshes with the rack gear, then the protrusion member position is precisely controlled, but the protrusion member cannot be easily adjusted or removed
Solution Approach 1:
A portion of the rack gear teeth is extracted to create a gap region. This gap allows the pinion gear to be disengaged from the rack gear, enabling the protrusion member to be adjusted or removed independently while maintaining precise position control during normal operation when the gears are engaged.
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
The device effectively suppresses the drooping of sheet end portions, ensuring accurate and efficient stacking on the tray, thereby improving the overall sheet handling process in image forming systems.
Implementation Method 1
The movement mechanism includes a rotation shaft and a plurality of gears. The rotation shaft extends parallel to the center axis of the ejection roller pair. The gears include a pinion gear which is supported by the rotation shaft and a rack gear which is formed in the protrusion member. The pinion gear and the rack gear are engaged.
Data Source
AI summary
A sheet ejection device includes an ejection roller pair, a stacking tray, a protrusion member and a movement mechanism. The protrusion member is supported to be able to reciprocate between a protrusion position and a retraction position in a predetermined movement direction. The movement mechanism includes: a rotation shaft; a holding member; and a rack and pinion mechanism which includes a pinion gear and a rack gear. In at least a part of the rack gear in the movement direction, a narrow width region is provided which includes a narrow width gear and a cutout portion. In the narrow width region, the pinion gear is slidable between a meshing position and a release position, and in a state where the pinion gear has slid to the release position, the protrusion member can be relatively moved with respect to the pinion gear in the movement direction.