Sheet Conveyance Speed Control for Accurate Skew Correction
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Solution Overview
Problem
Existing sheet conveyance devices face issues with varying conveyance speeds due to sheet rigidity, surface texture, and resistance, leading to inaccuracies in skew correction and leading end position, especially under high productivity conditions.
Innovation Solution
A sheet conveyance device with a control unit that adjusts the conveyance speed of pre-registration rollers based on sensor detections, using multiple sensors to precisely control the speed of the first and second conveyance roller pairs to correct skew by forming a loop, ensuring accurate alignment before reaching the registration roller pair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional skew correction mechanism is used with fixed conveyance speed, then the structure is simple, but the conveyance speed varies depending on sheet rigidity, surface texture, and resistance, causing timing variations and deteriorating correction accuracy
Solution Approach 1:
The patent applies dynamics by making the conveyance speed of the first conveyance roller pair variable rather than fixed. The control unit dynamically adjusts the conveyance speed based on real-time detection results from sensors, allowing the system to adapt to variations in sheet properties and conveyance conditions, thereby maintaining high correction accuracy under diverse operating conditions
Solution Approach 2:
The patent implements feedback control by using sensors to detect the leading end of sheets at multiple positions and feeding this information back to the control unit. The control unit uses this feedback to adjust the conveyance speed of the first conveyance roller pair, creating a closed-loop system that continuously optimizes sheet conveyance timing and position for accurate skew correction
2Productivity
If the conveyance speed is increased to improve productivity, then more sheets can be processed per unit time, but the timing variation due to varying sheet properties increases, deteriorating leading end position accuracy
Solution Approach 1:
The system dynamically adjusts the conveyance speed based on actual sheet conditions rather than using a fixed high speed. The control unit monitors detection results and modulates the conveyance speed of the first conveyance roller pair in real-time, allowing the system to maintain high productivity when conditions permit while ensuring accurate timing and position when sheet variations occur
Solution Approach 2:
The feedback control system continuously monitors sheet position and timing information from sensors and uses this information to adjust conveyance speed. This closed-loop feedback mechanism ensures that even at high processing speeds, the system can compensate for timing variations caused by sheet property differences, maintaining both productivity and measurement precision
Data Source
AI summary
A sheet conveyance device includes a feeding unit, a first conveyance path, a registration roller pair, a first conveyance roller pair, a first sensor, a second sensor, and a control unit, wherein the control unit controls the first conveyance roller pair to correct skew of the sheet, and when a sheet is conveyed from the first conveyance roller pair toward the registration roller pair, in a case where a time is a first time, the control unit controls the conveyance of the sheet so that the sheet is conveyed toward the second sensor at a first speed, and in a case where a time is a second time longer than the first time, the control unit controls the conveyance of the sheet so that the sheet is conveyed toward the second sensor at a second speed larger than the first speed.