Sheet Distortion Correction in Image Forming Apparatus
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Solution Overview
Problem
When continuous sheets are rewound and reprinted, they often develop wrinkles due to thermal contraction and toner image distortion, leading to partial distortion and curling issues.
Innovation Solution
An image forming apparatus with a distortion correction section that includes a distortion detection system to identify and correct sheet distortion by humidifying the sheet using paired humidification rollers, adjusting their pressure contact based on detected distortion and toner image information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous sheet is rewound and reprinted to improve work efficiency and reduce printing time, then productivity is improved, but wrinkles and distortion occur in the sheet due to thermal contraction
Solution Approach 1:
The distortion detection section detects sheet distortion before the sheet enters the fixing portion, and the distortion correction section applies correction in advance by adjusting sheet tension or position, preventing wrinkles from forming during the fixing process while enabling continuous sheet rewinding for improved productivity
2Reliability
If the sheet is heated and pressurized in the fixing portion to fix the toner image, then the toner image is properly fixed, but the sheet contracts and causes distortion
Solution Approach 1:
The distortion detection section provides real-time feedback on sheet distortion caused by thermal contraction in the fixing portion, allowing the distortion correction section to dynamically adjust sheet tension or positioning to compensate for contraction effects while maintaining proper toner image fixation
3Shape
If the distortion correction section humidifies the sheet to correct distortion, then sheet distortion is reduced, but the device complexity increases
Solution Approach 1:
The distortion correction section changes physical parameters of the sheet such as humidity or temperature in a controlled manner to correct distortion, using adjustable rollers or heating elements that modify sheet properties temporarily to eliminate wrinkles without requiring complex mechanical intervention
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
Prevents wrinkles and corrects distortion in the sheet during rewinding and re-printing processes, ensuring improved print quality and reduced curling.
Implementation Method 1
the distortion correction section causes the pair of humidification rollers to be in pressure-contact with the sheet when the sheet is conveyed in the second conveyance direction and distortion occurs in the sheet
Implementation Method 2
the toner image is directly or indirectly transferred to a sheet, heated, pressurized and fixed by a fixing nip
Implementation Method 3
they often develop wrinkles due to thermal contraction and toner image distortion
Data Source
Figure 1
Figure 2
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AI summary
An image forming apparatus includes: a conveyance section configured to convey a sheet in a direction opposite to a first conveyance direction during image formation, the direction being a second conveyance direction; and a distortion correction section disposed on an upstream side of a transfer nip in the first conveyance direction and configured to correct, when the sheet is conveyed by the conveyance section in the second conveyance direction, distortion of the sheet generated when the sheet passes through a fixing nip.