Sheet Conveyance Roller Control for Thin and Thick Paper Skew Correction
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Solution Overview
Problem
Existing image forming apparatuses face challenges in achieving accurate skew correction for sheets of varying stiffness and material types, particularly thick and thin papers, due to warping and curvature issues in the conveyance path.
Innovation Solution
A sheet conveyance apparatus with multiple roller pairs and a control unit that adjusts skew correction modes based on sheet grammage, performing skew correction by abutting the leading edge against specific roller pairs in stopped states or allowing passage without abutment, depending on sheet stiffness, to ensure accurate alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If skew correction is performed by abutting the leading edge of the sheet against the second roller pair in a stopped state, then skew correction accuracy is improved for thick paper, but the sheet may warp or fail to align properly for thin paper
Solution Approach 1:
The system dynamically switches between two skew correction modes based on sheet grammage detection. For thick paper (first grammage), the leading edge is abutted against the second roller pair in stopped state. For thin paper (second grammage), the leading edge is passed through without abutment, and skew correction is performed at the third roller pair instead. This dynamic adaptation resolves the contradiction by selecting the appropriate correction method for each sheet type.
Solution Approach 2:
The control unit changes the operational parameters of the roller pairs based on sheet grammage. When thin paper is detected, the system modifies the stopped state timing and abutment position of the roller pairs to prevent warping while still achieving skew correction. This parameter change allows the same hardware to reliably handle different sheet types.
2Stability of the object's composition
If the leading edge of the sheet is passed through the second roller pair without abutting against it in a stopped state, then warping is reduced for thin paper, but skew correction accuracy may be insufficient for thick paper
Solution Approach 1:
The system dynamically selects which roller pair performs the primary skew correction function based on sheet type. For thin paper, the third roller pair becomes the primary correction point while the second roller pair allows passage. For thick paper, the second roller pair performs correction while the third roller pair allows passage. This dynamic role assignment maintains both flatness and accuracy.
Solution Approach 2:
The third roller pair serves as an intermediary correction point for thin paper, compensating for the skipped abutment at the second roller pair. This intermediary mechanism ensures that skew correction is still achieved even when the primary abutment method is bypassed to prevent warping.
3Manufacturing precision
If skew correction is performed at both the second and third roller pairs in stopped state, then skew correction accuracy is maximized, but the complexity of the control system increases
Solution Approach 1:
The control system dynamically activates only the necessary roller pair for skew correction based on sheet grammage detection. This dynamic activation reduces the effective complexity by avoiding simultaneous operation of both correction mechanisms, while still providing maximum correction accuracy when needed through selective activation.
Data Source
AI summary
A sheet conveyance apparatus includes a first roller pair, a second roller pair, a third roller pair, and a control unit configured to execute a first mode in which skew correction of the sheet is performed by abutting a leading edge of the sheet against the second roller pair in a stopped state, and then the sheet is passed through the third roller pair without abutting the leading edge of the sheet against the third roller pair in a stopped state, and a second mode in which the leading edge of the sheet is passed through the second roller pair without abutting against the second roller pair in the stopped state, and then skew correction of the sheet is performed by abutting the leading edge of the sheet against the third roller pair in the stopped state.