Sheet Discharger Hold-Down Control for Curled Sheet Stability
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Solution Overview
Problem
Existing sheet dischargers in image forming apparatuses and post-processors face issues such as disordering of sheets on the discharge tray due to pushing and curling of sheets, which can lead to discharge failures.
Innovation Solution
A sheet discharger with a discharge member, discharge tray, hold-down member, and control portion that dynamically adjusts the hold-down operation based on sheet characteristics, such as curl direction and type, to prevent sheet interference and discharge failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a sheet is discharged on the discharge tray through the sheet discharge outlet, then the sheet is successfully discharged, but the sheet may push out loaded sheets causing disorder or sheet fall
Solution Approach 1:
The hold-down member is actuated in advance before the discharged sheet reaches the discharge tray to preemptively hold down any previously discharged sheets. This preliminary action prevents the newly discharged sheet from pushing out loaded sheets, thereby maintaining sheet loading stability without compromising discharge efficiency.
2Ease of operation
If a largely curled sheet is discharged in a curled state, then the discharge process is simple, but the sheet may clog the discharge outlet causing discharge failure
Solution Approach 1:
The hold-down member is actuated before the curled sheet reaches the discharge outlet to apply downward force, preliminarily flattening the sheet. This prevents the curled sheet from clogging the discharge outlet during the discharge process, thereby maintaining both operational simplicity and discharge reliability.
Solution Approach 2:
The hold-down member serves as an intermediary mechanism between the discharged sheet and the discharge outlet. By applying downward force through this intermediary component, the system effectively manages curled sheets without requiring complex discharge mechanisms, thus maintaining simplicity while improving reliability.
3Reliability
If the sheet hold-down member is always in the hold-down position, then sheet disorder is prevented, but the member cannot accommodate sheet characteristics variations
Solution Approach 1:
The hold-down member is designed with dynamic positioning capability, allowing it to switch between hold-down and retracted positions based on sheet characteristics. This dynamic adjustment enables the system to adapt to varying sheet properties (such as curling tendencies) while maintaining sheet loading stability through selective engagement of the hold-down function.
Solution Approach 2:
The system changes the positional parameter of the hold-down member based on detected sheet characteristics. By adjusting this parameter dynamically, the system can accommodate different sheet types and conditions, maintaining both reliability for sheet stability and adaptability for varying sheet characteristics.
Data Source
AI summary
A sheet discharger includes a sheet discharge outlet, a discharge member, a sheet discharge tray, a sheet hold-down member, a drive portion, and a control portion. The sheet discharge tray is disposed downstream from the sheet discharge outlet with respect to a discharge direction and is a tray on which a sheet discharged through the sheet discharge outlet is loaded. The sheet hold-down member is swingable between a hold-down position at which the sheet loaded on the sheet discharge tray is held down at an upstream part thereof in the discharge direction and a retracted position retracted upward from the hold-down position. The drive portion drives the sheet hold-down member. The control portion determines, in accordance with characteristics of the sheet, whether or not to execute a sheet hold-down operation in which the sheet hold-down member is moved to the retracted position and to the hold-down position.