Image Forming Apparatus Curl Correction Mechanism
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in curl correction, particularly with high-speed operations and diverse sheet types, leading to paper jams and image quality issues due to varying curl formations and the need for complex adjustments in curl correcting mechanisms.
Innovation Solution
The apparatus employs multiple fixing devices and strategically positioned curl applying units on divergent and joined conveyance paths to apply and correct curls, optimizing curl correction based on sheet type and temperature, ensuring effective curl management and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single curl correcting unit is disposed downstream of the fixing device, then the structure is simple, but the curl correction is insufficient for diverse sheet types and high-speed operations
Solution Approach 1:
The curl correction function is divided into multiple independent units: a first curl correcting unit disposed downstream of the fixing device, and a second curl correcting unit disposed upstream of the fixing device. Each unit can independently correct curls generated under different conditions, enabling effective curl management for diverse sheet types without excessive structural complexity.
Solution Approach 2:
The second curl correcting unit is positioned upstream of the fixing device to perform preliminary curl correction before the sheet enters the fixing device. This prevents excessive curl formation during fixing, particularly for thin sheets that are prone to large curl under high-speed operation conditions.
2Productivity
If the fixing temperature and applied pressure are increased for high-speed operation, then the productivity is improved, but the curl level becomes higher causing paper jams
Solution Approach 1:
The second curl correcting unit is positioned upstream of the fixing device to perform preliminary curl correction before the sheet enters the fixing device. This prevents excessive curl formation during fixing, particularly for thin sheets that are prone to large curl under high-speed operation conditions.
Solution Approach 2:
The apparatus includes a sheet type detection mechanism that detects whether the sheet is thin or thick, and accordingly controls the operation of the second curl correcting unit. This feedback-based control ensures that curl correction is applied only when necessary, maintaining high-speed operation while preventing paper jams.
3Manufacturing precision
If a long roller is disposed downstream of the fixing device to remove image traces, then the image quality is improved, but a gap is formed between the guiding board and the roller causing paper jam when curl level is high
Solution Approach 1:
The second curl correcting unit is positioned upstream of the fixing device to perform preliminary curl correction before the sheet enters the fixing device. This prevents excessive curl formation during fixing, particularly for thin sheets that are prone to large curl under high-speed operation conditions.
4Adaptability or versatility
If the curl correcting capability is adjusted for different sheet types, then the adaptability is improved, but the device complexity and operation sequence become complex
Solution Approach 1:
The curl correction function is divided into multiple independent units: a first curl correcting unit disposed downstream of the fixing device, and a second curl correcting unit disposed upstream of the fixing device. Each unit can independently correct curls generated under different conditions, enabling effective curl management for diverse sheet types without excessive structural complexity.
Solution Approach 2:
The apparatus includes a sheet type detection mechanism that automatically detects whether the sheet is thin or thick, and accordingly controls the operation of the second curl correcting unit. This self-service capability eliminates the need for manual adjustment, simplifying operation while maintaining high adaptability to different sheet types.
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
This solution effectively corrects curls on both thin and thick papers, preventing paper jams and ensuring precise registration and high-quality imaging, even at high speeds, by dynamically adjusting curl applying capabilities and directions.
Implementation Method 1
the sheet is arched on an image formed side due to heat contraction of the toner
Implementation Method 2
moisture is evaporated from the sheet due to heat of the fixing device
Data Source
AI summary
An image forming apparatus a first fixing device fixing the toner image on the sheet; a second fixing device fixing the toner image, fixed on the sheet by the first fixing device; a fixing conveyance path guiding the sheet carrying the toner image fixed by the second fixing device; a detour conveyance path diverging from the fixing conveyance path on an upstream side of the second fixing device, and joining the fixing conveyance path at a joining point on a downstream side of the second fixing device so that the sheet is guided detouring the second fixing device; a joined conveyance path guiding the sheet on a downstream side of the joining point; a first curl applying unit disposed on the joined conveyance path and applying a curl to the sheet; and a second curl applying unit disposed on the detour conveyance path and applying a curl to the sheet.