Swingable Roller Arm for Skew Correction in Sheet Conveyance
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Solution Overview
Problem
Existing sheet conveying apparatuses face challenges in stabilizing sheet conveyance while preventing skewing after skew correction, leading to uneven image quality in high-image-quality ink jet recording, and require additional motors or increased size for effective skew correction.
Innovation Solution
A conveying apparatus with a first pair of rollers driven by a swingable arm member that increases pressure against the pinch roller with increasing conveyance resistance, and a second pair of rollers rotating opposite to the first pair to correct skew, ensuring stable conveyance and minimizing skew recurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conveying rollers are moved in the axial direction to eliminate thrust force from warp, then skew recurrence is prevented, but sheet conveyance stability deteriorates before skew correction
Solution Approach 1:
The conveying roller is configured to be movable in the axial direction, transitioning from a fixed state during normal conveyance to a movable state during skew correction. This dynamic adjustment allows the roller to shift position when the sheet contacts the resist roller, eliminating thrust force from warp while maintaining stable conveyance positioning during normal operation.
Solution Approach 2:
The system applies preliminary positioning by maintaining the conveying roller in a fixed position during normal conveyance, preventing instability. When skew correction is needed, the roller is allowed to move axially to counteract the thrust force generated by sheet warp, thereby preventing skew recurrence before the sheet reaches the image forming portion.
2Device complexity
If conveying roller is integrally provided relative to rotational direction, then structural simplicity is maintained, but skew correction effectiveness deteriorates for large skew amounts
Solution Approach 1:
The conveying roller is configured to be movable in the axial direction, transitioning from a fixed state during normal conveyance to a movable state during skew correction. This dynamic adjustment allows the roller to shift position when the sheet contacts the resist roller, eliminating thrust force from warp while maintaining stable conveyance positioning during normal operation.
Solution Approach 2:
The roller support structure is segmented into a fixed portion and a movable portion, allowing the conveying roller to be independently positioned in the axial direction. This segmentation enables the roller to shift position for skew correction while maintaining its integral structure for rotational drive, resolving the contradiction between structural simplicity and correction effectiveness.
3Reliability
If slippage between sheet and conveying roller is increased to eliminate warp, then warp elimination is improved, but conveying force deteriorates
Solution Approach 1:
The conveying roller is configured to be movable in the axial direction, transitioning from a fixed state during normal conveyance to a movable state during skew correction. This dynamic adjustment allows the roller to shift position when the sheet contacts the resist roller, eliminating thrust force from warp while maintaining stable conveyance positioning during normal operation.
Solution Approach 2:
The sheet warp, which generates harmful thrust force causing skew recurrence, is converted into a beneficial mechanism. When the sheet contacts the resist roller, the warp-induced thrust force drives the conveying roller to move axially, which in turn eliminates the warp and prevents skew recurrence. The harmful thrust force is thus transformed into a useful corrective action.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively restrains skew recurrence and ensures stable sheet conveyance, maintaining high image quality by adjusting the force dynamics between rollers to correct skew and eliminate warp, thereby preventing uneven image formation.
Implementation Method 1
a force for pressing the drive roller against the pinch roller increases as a conveyance resistance of the sheet increases
Implementation Method 2
a leading end of the sheet sandwiched by the first pair of rollers is pressed against the second pair of rollers which is rotating in a direction opposite from that of the first pair of rollers
Data Source
AI summary
A conveying apparatus includes a first pair of rollers having a drive roller and a pinch roller driven by the drive roller, a second pair of rollers provided downstream of the first pair of rollers, and an arm member supporting the drive roller and adapted to be swingable such that a force for pressing the drive roller against the pinch roller increases as a conveyance resistance of the sheet increases. The force for pressing the drive roller against the pinch roller decreases if driven by the moving sheet. The conveying speed of the second pair of rollers is set to be higher than the conveying speed of the drive roller so as to cause the drive roller to be driven by the sheet in the case where a skew of the sheet has been corrected and the sheet having the skew corrected is conveyed by the second pair of rollers.