Sheet Feeding Apparatus with Segmented Stacking and Height Control
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Solution Overview
Problem
Existing sheet feeding apparatuses face issues with feeding sheets of uneven thickness, such as envelopes or embossed sheets, leading to height differences in the sheet bundle, which can cause uneven contact pressure and result in sheet feeding failures like oblique conveyance or duplicate feeding, and may erroneously detect 'NO SHEET' even when sheets are present due to misplaced detection sensors.
Innovation Solution
A sheet feeding apparatus with a movable stacking portion, a lifting mechanism, and multiple detection sensors that control the lifting operation based on signals from both the sheet height detection sensor and the sheet presence detection sensor to maintain the topmost sheet within a feasible feeding range, ensuring accurate detection and prevention of feeding failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sheets with uneven thickness are stacked on the sheet stacking portion, then the sheet bundle can be formed, but height differences are caused on the upper surface of the stacked sheet bundle
Solution Approach 1:
The sheet stacking portion is divided into a first sheet stacking region and a second sheet stacking region. The first region stacks sheets with uniform thickness, while the second region stacks sheets with uneven thickness (such as envelopes with flaps). This segmentation allows each region to handle specific sheet types, preventing height differences from affecting the entire sheet bundle while maintaining the ability to stack large quantities of various sheet types.
2Productivity
If a feeding roller feeds sheets with uneven contact pressure, then feeding speed can be maintained, but sheet feeding failure such as oblique conveyance or duplicate feeding is caused
Solution Approach 1:
A pressurizing roller is introduced as an intermediary component between the feeding roller and the sheets. The pressurizing roller applies uniform pressure to the sheets in the feeding direction, ensuring even contact pressure across the sheet surface. This mediator component prevents feeding failures such as oblique conveyance or duplicate feeding while maintaining efficient feeding speed.
3Measurement precision
If the sheet height detection sensor is disposed downstream to detect the upper surface of sheets, then the sheet height can be detected, but erroneous 'NO SHEET' detection occurs when height difference is large
Solution Approach 1:
The detection system is segmented into two independent detection paths: a first sheet height detection sensor for detecting sheet height in the first sheet stacking region, and a second sheet height detection sensor for detecting sheet height in the second sheet stacking region. Each sensor independently monitors its respective region, preventing erroneous detection caused by height differences between different sheet types.
Solution Approach 2:
Different detection methods are applied to different regions based on their specific characteristics. The first sheet stacking region (uniform thickness sheets) uses one detection approach, while the second sheet stacking region (uneven thickness sheets) uses another detection approach optimized for height variations. This local quality adaptation ensures reliable detection in both regions.
4Productivity
If a large number of sheets are stacked to meet high-speed printing needs, then productivity increases, but the height difference between downstream and upstream sides becomes large
Solution Approach 1:
The sheet stacking portion is divided into a first sheet stacking region for uniform thickness sheets and a second sheet stacking region for uneven thickness sheets. This segmentation allows the system to stack large quantities of sheets while preventing excessive inclination by directing different sheet types to appropriate regions, maintaining sheet bundle stability even at high capacities.
Data Source
AI summary
A sheet feeding apparatus includes a stacking portion, a lifting portion, a feeding portion, and a control portion. The sheet feeding apparatus further includes a first height detecting portion configured to output a signal corresponding to a position in a height direction of the topmost sheet of sheets stacked on the stacking portion, a sheet presence detecting portion configured to output a signal corresponding to presence or absence of the sheets stacked on the stacking portion, and a second height detecting portion configured to output a signal corresponding to a position in a height direction of the stacking portion. The control portion performs control for sheet feeding operation using the signal from the sheet presence detecting portion if the position of the stacking portion is above a predetermined height based on the signal from the second height detecting portion and, if the position of the stacking portion is below the predetermined height, the control portion performs control for sheet feeding operation not using the sheet presence detecting portion.