Sheet Stacker Airflow Control for Precise Sheet Detachment
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Solution Overview
Problem
Existing sheet stackers in image forming apparatuses face issues with sheet dropping during transportation due to inconsistent air volume and speed differences, leading to misalignment and collisions, particularly when dealing with varying sheet sizes.
Innovation Solution
A sheet stacker system with a guiding member and multiple blowers that adjust air volume and speed based on sheet size, using a controller to optimize the detachment and falling process, minimizing sheet dropping and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fan discharges air to assist sheet retention and cooling, then sheet retention and cooling are improved, but sheet positioning precision deteriorates due to air flow inconsistency
Solution Approach 1:
The patent divides the air blowing function into multiple independent blowers (first blower and second blower) positioned at different locations. The first blower handles sheet retention during transport, while the second blower handles sheet cooling and positioning. This segmentation allows each blower to be optimized for its specific function, improving overall precision while maintaining reliability.
Solution Approach 2:
Different regions of the sheet processing path receive different air flow characteristics. The first blower provides stronger air flow for retention at the transport path, while the second blower provides gentler air flow for cooling and positioning at the stacking region. This local differentiation of air flow quality improves both retention reliability and positioning precision.
2Reliability
If sheet-transporting speed is accelerated to increase speed difference for detachment, then sheet detachment is improved, but sheet positioning precision deteriorates due to speed inconsistency
Solution Approach 1:
The patent employs dynamic speed control of the guiding member that adapts to different sheet sizes. The guiding member accelerates to create speed difference for detachment, then decelerates to control the falling trajectory. This dynamic adjustment ensures reliable detachment while maintaining precise stacking position, resolving the contradiction between detachment reliability and positioning precision.
Solution Approach 2:
The system changes the speed parameter of the guiding member based on detected sheet size. For larger sheets, higher speeds are used to ensure detachment; for smaller sheets, lower speeds are used to maintain positioning precision. This parameter adaptation allows the system to achieve both reliable detachment and precise stacking across varying sheet dimensions.
3Productivity
If air volume is increased to accelerate sheet falling, then sheet stacking speed is improved, but sheet positioning precision deteriorates due to excessive air flow
Solution Approach 1:
The air blowing function is segmented into two stages: the first blower provides air flow for retention during transport, and the second blower provides controlled air flow for accelerating the falling sheet. This segmentation allows the second blower to be optimized for acceleration without compromising alignment, as the sheet is already positioned by the guiding member before the second blower activates.
Solution Approach 2:
The guiding member acts as an intermediary between the transporting member and the stacking tray. It controls the sheet's movement and positioning, then releases it to fall. The second blower works in conjunction with this intermediary to provide controlled acceleration during the falling phase, ensuring both speed and precision are achieved.
4Reliability
If sheet-transporting device speed is accelerated just before stacking position, then sheet detachment reliability is improved, but energy consumption increases
Solution Approach 1:
The guiding member uses dynamic acceleration only when needed for detachment, rather than maintaining high speed continuously. After detachment, the guiding member decelerates to control the falling trajectory. This dynamic operation reduces energy consumption compared to continuous high-speed operation, while maintaining detachment reliability through targeted acceleration phases.
Solution Approach 2:
The system employs periodic acceleration and deceleration cycles of the guiding member rather than continuous high-speed operation. Acceleration occurs only during the detachment phase, followed by deceleration during the controlled fall. This periodic action pattern reduces overall energy consumption while achieving reliable detachment when required.
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 system ensures accurate stacking by adjusting air volume and speed to match sheet size, reducing misalignment and collisions, and maintaining consistent sheet positioning on the tray.
Implementation Method 1
The plurality of blowers discharge air flows towards the sheet that is transported to the stacking member
Implementation Method 2
the air flow discharged from the blower is blown onto the surface of the falling sheet to push out the air trapped between stacked sheets on the tray, thereby releasing air between the sheets
Data Source
AI summary
A sheet stacker includes a stacking member, transporting member, guiding member, a plurality of blowers, and controller. A sheet is stacked on the sheet stacker. The transporting member transports a sheet in a sheet-transporting direction towards the stacking member. The guiding member retains an edge portion of the sheet transported by the transporting member in a standby position, followed by moving in the sheet-transporting direction to guide transporting of the sheet. The blowers discharge air flows towards the sheet transported to the stacking member. The air flows are directed towards a top plane of the stacking member. One of the blowers is disposed in a position corresponding to the detaching position. The controller controls motions of the blowers and air volumes from the blowers based on information regarding a length of the transported sheet.