Sheet Stacking Device with Door-Interlocked Elevation Mechanism
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Solution Overview
Problem
Existing sheet stacking devices in image forming apparatuses face issues with productivity reduction due to the need to stop the device for removing full sheet stacks and potential damage from motor malfunctions causing unintended movement of the sheet stacking table, especially when the motor malfunctions lead to accidental raising of the table.
Innovation Solution
A sheet stacking device with a movable sheet stacking unit, an elevation unit driven by a motor, and a transmission system that allows only downward movement when the front door is open, preventing accidental upward movement and enabling continuous operation without interrupting the image forming process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet stacking table is raised or lowered by a motor controlled by a control unit, then the sheet stacking operation can be automated and productivity is improved, but if the motor causes a malfunction due to electrical noise or the like, the sheet stacking table may be moved beyond the predetermined range causing damage
Solution Approach 1:
The patent applies beforehand cushioning by providing a limiting mechanism with upper and lower stoppers that prevent the sheet stacking table from moving beyond the predetermined range. This mechanical limitation is established in advance to cushion against potential motor malfunctions caused by electrical noise or other issues, ensuring the table cannot be moved to a position that would cause damage even if the motor fails.
Solution Approach 2:
The patent uses an intermediary approach by introducing a limiting mechanism that acts as a mediator between the motor and the sheet stacking table. This mechanism includes stoppers that physically intervene to prevent excessive movement, serving as a safety intermediary that protects the system from motor malfunctions while allowing normal automated operation.
2Reliability
If the sheet stacking table is forcibly stopped when it knocks against upper or lower stoppers, then damage from motor malfunction is prevented, but the top of a sheet stack may bump into upper parts of the device before the table is stopped causing damage
Solution Approach 1:
The patent applies beforehand cushioning by positioning the stoppers at predetermined locations that are safer than the previous arrangement. The upper stopper is positioned at a height that prevents the sheet stack from bumping into upper parts of the device, and the lower stopper is positioned to prevent the table from moving too far downward. This cushions against the harmful effects of motor malfunction before they can cause damage.
Solution Approach 2:
The patent implements feedback by using a sheet surface detection sensor to detect the position of the top surface of the sheet stack. This feedback information is used to control the motor, allowing the system to respond to the actual position of the sheet stack and prevent bumping damage while maintaining automated operation.
3Productivity
If the sheet stacking table is lowered and placed onto a dolly for sheet stack removal, then sheet stacks can be removed without stopping the image forming apparatus, but the device complexity increases due to the additional dolly and removal mechanism
Solution Approach 1:
The patent applies dynamics by making the sheet stacking table movable between a stacking position and an ejection position. The table can be dynamically adjusted to lower onto the dolly for sheet stack removal and then raised back to the stacking position for continuous operation, allowing the system to adapt its configuration based on operational needs.
Solution Approach 2:
The patent implements self-service by enabling the sheet stacking table to automatically lower onto the dolly and be removed without requiring manual intervention or stopping the image forming apparatus. The system serves itself by automating the sheet stack removal process through the dolly mechanism.
Data Source
AI summary
A stacker includes a plurality of sheet stacking units individually movable upward and downward. Sheets are selectively stacked onto either of the stacker trays. To remove the sheets stacked on one of the stacker trays, a door is opened. In a state where the door is open, the stacker trays moved by respective elevation units are movable only downward. In this manner, accidental upward movement of each of the stacker trays caused by a malfunction of a motor or the like is regulated, whereby damage to the stacker is prevented.