Curl Correction Nip Width and Guide Member Protrusion
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Solution Overview
Problem
Existing curl correction apparatuses using a hard roller and a soft roller suffer from image failure and unevenness due to unfixed toner accumulation and temperature differences between the rollers, leading to inconsistent image fixing.
Innovation Solution
A curl correction apparatus with a hard roller and a soft roller, where the nip width between them is narrower in the central portion than at the ends, and a guide member is used to protrude towards the downstream, guiding the sheet to ensure uniform contact and reduce toner accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a backup roller is disposed toward the hard roller to back up the biting force in the central portion, then the biting force balance is improved, but unfixed toner accumulates on the backup roller causing image failure
Solution Approach 1:
The invention removes the backup roller from the system entirely. Instead of adding a component to support the central portion, the patent uses a guide member that protrudes into the nip region to redirect the sheet, allowing the sheet to contact the hard roller at the central portion without requiring additional support structures that would accumulate toner.
Solution Approach 2:
The guide member acts as an intermediary element that mediates between the sheet and the hard roller. By protruding into the nip region, the guide member directs the sheet to contact the hard roller at the central portion, effectively distributing the biting force without introducing new components that would accumulate toner.
2Length of stationary object
If the hard roller and soft roller are bent by reaction force at the nip portion, then the axial distance between central portions increases, but the biting force in the central portion becomes smaller
Solution Approach 1:
The guide member is positioned to protrude into the nip region before the sheet enters, preliminarily guiding the sheet to contact the hard roller at the central portion. This pre-positioning ensures that the sheet applies force to the central region of the hard roller, compensating for the bending effect and maintaining adequate biting force in the central portion.
3Ease of operation
If a guide member protrudes into the nip region to guide the sheet, then sheet guidance is improved, but the complexity of the apparatus increases
Solution Approach 1:
The guide member is designed with local quality by protruding only in the central portion of the nip region while maintaining a simpler structure at the end portions. This localized modification provides effective sheet guidance in the critical central region without requiring complex structures throughout the entire apparatus.
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 configuration reduces image failure and unevenness by ensuring consistent curl correction and preventing toner accumulation, resulting in improved image quality.
Implementation Method 1
a hard roller and a soft roller pressed against the hard roller, and corrects the curl of the sheet at a nip between the rollers
Implementation Method 2
a heating apparatus configured to heat a sheet having a toner image
Data Source
AI summary
A curl correction apparatus that corrects a curl of a sheet includes: a hard roller that is disposed in the downstream in a sheet conveying direction of a heating apparatus; a soft roller that is disposed in the downstream in the sheet conveying direction of the heating apparatus; and a guide member that is disposed in the immediate upstream in the sheet conveying direction with respect to the hard roller, and guides the sheet; wherein a nip width in the sheet conveying direction of a nip portion between the hard roller and the soft roller is set to be narrower in a central portion in an axial direction than end portions in the axial direction, and the guide member is configured to protrude in the central portion in the axial direction toward the downstream in the sheet conveying direction from the both end portions in the axial direction.