Dynamic Sheet Conveyance Speed Control for Duplex Jam Prevention
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Solution Overview
Problem
Image forming apparatuses face challenges in achieving stable duplex printing while preventing sheet jamming and maintaining productivity, as the required duplex standby time often conflicts with the need for efficient re-feeding timing.
Innovation Solution
The implementation of a control unit that manages conveyance speeds and re-conveyance timing in image forming systems, allowing for faster initial conveyance and controlled deceleration to match image formation timing, thereby optimizing duplex standby time and preventing jams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pre-registration stop time is extended to absorb conveyance timing variation, then sheet clogging is prevented, but productivity decreases
Solution Approach 1:
The patent applies dynamics by making the conveyance speed variable rather than constant. The conveyance unit dynamically adjusts speed between a first conveying speed (during normal operation) and a second conveying speed (when sheet timing variation is detected), allowing the system to adapt to timing variations without requiring extended stop times, thus maintaining both reliability and productivity
Solution Approach 2:
The patent changes the parameter of conveyance speed to resolve the contradiction. By detecting sheet timing variation and adjusting the conveyance speed parameter accordingly (switching between first and second conveying speeds), the system absorbs timing variations dynamically without requiring fixed extended stop times that would reduce productivity
2Productivity
If the pre-registration stop time is shortened to improve productivity, then printing efficiency increases, but sheet clogging occurs
Solution Approach 1:
The patent implements feedback by detecting the actual conveyance timing of sheets and using this information to adjust the conveyance speed. The detection unit monitors sheet timing, and when variation is detected, the control unit adjusts the conveyance speed to prevent clogging, creating a closed-loop system that maintains reliability while minimizing stop time for maximum productivity
Solution Approach 2:
The system transitions from static fixed stop-time registration to dynamic speed-adjustment registration. The conveyance unit responds in real-time to detected timing variations by adjusting speed, allowing productivity to be maintained while preventing clogging through adaptive control rather than conservative fixed timing
3Productivity
If faster conveyance speed is used to improve productivity, then printing efficiency increases, but conveyance timing variation increases causing misalignment
Solution Approach 1:
The patent uses feedback to maintain precision during high-speed operation. The detection unit continuously monitors sheet conveyance timing, and when variation is detected that would cause misalignment, the control unit adjusts the conveyance speed to compensate, ensuring accurate sheet-image alignment even when operating at faster speeds for improved productivity
Solution Approach 2:
The system employs dynamic speed adjustment to maintain alignment precision. By switching between first and second conveying speeds based on detected timing variation, the system can operate at high speeds when timing is stable and slow down when variation occurs, maintaining manufacturing precision while maximizing productivity
Data Source
AI summary
An image forming apparatus includes an accommodating portion, an image forming unit, a skew correcting portion, a conveyance unit, a detection unit, a re-conveyance unit, and a control unit. The control unit controls the re-conveyance unit such that the re-conveyance unit stops a sheet in the second conveyance path temporarily and starts to convey the sheet at a first timing after a second timing and before a third timing, where the second timing is a timing such that if the sheet is started to convey to the first conveyance path at the second timing, the conveyance unit decelerates the conveyance speed when the sheet reaches to the detection unit, and the third timing is a timing such that if the sheet is started to convey to the first conveyance path at the third timing, the conveyance unit decelerates the conveyance speed when the sheet reaches to the skew correcting portion.