Sheet Decurling via Water Content Control and Bending
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Solution Overview
Problem
Curled sheets caused by uneven water evaporation and absorption during the electro-photographic process pose challenges in conveyance, image processing, and stacking, as existing mechanical decurling methods fail to effectively flatten thin sheets like bond paper.
Innovation Solution
A sheet processing apparatus with a water content control unit that applies water to both surfaces of the sheet to reduce fiber elasticity, followed by a decurling section that applies a bending force to flatten the sheet, allowing for proper flattening of even thin sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If only physical bending force is used to decurl sheets, then relatively thick sheets can be decurled, but thin sheets like bond paper cannot be decurled
Solution Approach 1:
The invention changes the physical-chemical parameters of the sheet by controlling water content. By adjusting the water content to 10-15% before decurling, the fibers become more pliable and responsive to bending forces. This parameter change enables thin sheets like bond paper to be effectively decurled, while still maintaining effectiveness for thicker sheets.
Solution Approach 2:
The invention performs preliminary water content control before the decurling process. The water content is adjusted to an optimal range (10-15%) prior to applying bending force, which prepares the sheet fibers to respond better to the subsequent mechanical decurling action. This preliminary preparation enables effective decurling of thin sheets that would otherwise be resistant to mechanical forces alone.
2Strength
If strong bending force is applied to decurl thick sheets, then thick sheets can be flattened, but thin sheets may be damaged or still cannot be decurled
Solution Approach 1:
By controlling the water content parameter to 10-15%, the invention creates optimal conditions where moderate bending forces can effectively flatten sheets without causing damage. The hydrated fibers are more flexible and less prone to breaking, allowing reliable decurling across different sheet thicknesses and strengths.
3Manufacturing precision
If water is applied to reduce fiber elasticity, then thin sheets can be flattened by bending force, but additional process steps are required
Solution Approach 1:
The invention merges the water content control function with the existing decurling process. The water supply unit is integrated into the decurling device, combining two functions (moisturizing and mechanical flattening) into a single integrated system. This reduces overall process complexity while maintaining high flattening effectiveness.
Solution Approach 2:
The water content control is performed as a preliminary step before mechanical decurling. By pre-hydrating the fibers to the optimal water content range, the subsequent bending force becomes much more effective at flattening thin sheets, achieving high manufacturing precision without requiring excessively complex equipment.
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 apparatus effectively flattens curled sheets, resolving issues during conveyance, image processing, and stacking by applying water to reduce sheet elasticity before using a bending force, which was previously insufficient for thin sheets.
Implementation Method 1
water is applied to the both surfaces of the sheet to reduce the elasticity of the fibers which form the sheet
Implementation Method 2
the decurling section bends the curled sheet to be flat by a bending force
Implementation Method 3
water evaporates from the sheet due to the heat. Further, after the fixing, the sheet is open to the outside air, and thereby absorbs water from the outside air
Implementation Method 4
absorbs water from the outside air
Data Source
AI summary
A sheet processing apparatus which flattens a curled sheet includes: a water content control unit which controls a water content of a sheet to flatten the curled sheet; a decurling section which is provided downstream the water content control unit with respect to a conveyance direction of the sheet, and the decurling section bends the curled sheet to be flat by a bending force; and a conveyance route changing section which changes a conveyance route of the sheet to direct to the water content control unit or not.