Sheet Conveyance Speed Control for Printing Alignment
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Solution Overview
Problem
Existing image forming apparatuses face issues with sheet conveyance delays and misalignment due to slipping, leading to reduced productivity and potential sheet jams, especially during continuous printing jobs.
Innovation Solution
A sheet conveying device with speed control units that adjust the conveying speed of rollers based on sheet detection, increasing speed when a delay is detected and returning to normal speed at a determined point to stabilize conveyance and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conveying speed of the sheet is increased to make up for delays, then productivity is improved, but sheet spacing control deteriorates and may cause sheet jams
Solution Approach 1:
The conveying speed is made dynamic rather than constant. The speed control unit adjusts the conveying speed of the first conveying roller based on detected sheet spacing conditions, accelerating when spacing is excessive and decelerating when spacing is insufficient, thereby dynamically optimizing both productivity and spacing control
Solution Approach 2:
A feedback control mechanism is implemented where the sheet sensor continuously monitors the spacing between sheets and provides information to the speed control unit, which then adjusts the conveying speed accordingly. This closed-loop feedback system ensures that productivity improvements do not compromise sheet spacing control
2Manufacturing precision
If the conveying speed is rapidly changed to correct sheet positioning, then alignment is improved, but sheet stability deteriorates and may cause sheet damage
Solution Approach 1:
The system dynamically adjusts conveying speed based on real-time sheet position detection, but implements smooth acceleration and deceleration profiles rather than abrupt changes. The speed control unit calculates appropriate speed adjustments that achieve alignment correction while maintaining sheet stability through controlled rate of change
Solution Approach 2:
The system prepares for potential sheet instability by implementing gradual speed transitions and monitoring sheet position continuously. Before making speed changes, the system assesses the situation and applies cushioning control strategies that prevent sudden movements which could cause sheet damage
Data Source
AI summary
A sheet conveying device includes: a first conveying roller; a second conveying roller; a sheet sensor; and a speed control unit that controls a conveying speed of a sheet by each of the first conveying roller and the second conveying roller, the speed control unit being configured to change, where a leading edge of a second sheet has not been detected at a reference time point, the conveying speed by the first conveying roller from an initial speed to a high speed faster than the initial speed, maintain the conveying speed by the second conveying roller at the initial speed, determine return timing on the basis of a second elapsed amount, and return the conveying speed by the first conveying roller from the high speed to the initial speed at the determined return timing.