Sheet Conveying Device Dual-Phase Correction for Skew and Shift
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Solution Overview
Problem
Existing sheet conveying devices in image forming apparatuses face challenges in accurately correcting lateral shifts and skew deviations of recording media during transport, leading to inefficiencies in image formation processes.
Innovation Solution
A sheet conveying device equipped with multiple detectors and a rotary body that performs primary and secondary movements to detect and correct angle deviations and lateral shifts, ensuring precise alignment and positioning of the recording medium along the sheet conveying path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pair of conveying rollers conveys the recording medium and sensors detect positional shifts, then lateral shift and skew can be detected, but the correction precision is insufficient leading to image distortion
Solution Approach 1:
The patent divides the correction process into two distinct phases: primary correction performed by the first pair of sheet holding rollers based on initial detection, and secondary correction performed by the second pair of sheet holding rollers based on re-detection. This segmentation allows each correction stage to be optimized independently, with the first correction handling gross positional errors and the second correction refining the alignment precision, thereby resolving the contradiction between detection capability and correction accuracy.
2Productivity
If the recording medium is conveyed through the sheet conveying path, then the sheet can be transported, but angle deviation and lateral shift occur requiring complex correction mechanisms
Solution Approach 1:
The patent performs preliminary correction of the recording medium's angle deviation and lateral shift using the first pair of sheet holding rollers before the medium reaches the image forming section. By correcting positional errors in advance during the conveying process, the system maintains continuous productivity while preventing image distortion, thus resolving the contradiction between conveying efficiency and the need for correction mechanisms.
3Measurement precision
If multiple detectors are used to detect angle deviation and lateral shift, then measurement accuracy improves, but the device complexity increases
Solution Approach 1:
The patent employs detectors that serve multiple functions: the first detectors detect both angle deviation and lateral shift for primary correction, and the second detectors re-detect positional parameters for secondary correction. This multi-functional use of detection systems maximizes measurement precision while minimizing the total number of detectors required, thereby resolving the contradiction between measurement accuracy and device complexity.
Data Source
AI summary
A sheet conveying device, which is incorporated in an image forming apparatus, includes a first detector to detect an angle deviation of a recording medium to a sheet conveying direction, a second detector to detect a lateral shift of the recording medium to a width direction, a third detector to detect at least one of the angle deviation and the lateral shift after correction of the angle deviation detected by the first detector and the lateral shift detected by the second detector, and a rotary body to perform a primary movement by (1) rotating in the sheet conveying direction and returning to a reference position and by (2) moving in the width direction and returning to the reference position, and a secondary movement by performing at least one of (1) and (2) after the primary movement.