Pre-Transfer Guide Clearance Control for Sheet Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses, maintaining a consistent gap between guide members to ensure proper sheet alignment and prevent image defects is challenging due to variations in roller hardness and diameter, leading to potential braking force issues and alignment variations during sheet conveyance.
Innovation Solution
The apparatus includes a pivotable conveyance unit with a pre-transfer guide comprising independently swingable first and second guides, where the first guide is urged by a torsion spring to maintain contact with a contacted portion on the second guide, ensuring a fixed clearance and stable alignment, regardless of roller variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pre-transfer guide is provided to guide sheets to the transfer nip, then sheet alignment is improved, but the gap between guide members varies due to roller hardness and diameter variations, causing alignment instability
Solution Approach 1:
The first guide member is configured to be movable relative to the second guide member, allowing dynamic adjustment of the guide gap. This mobility enables the guide system to adapt to roller variations while maintaining consistent sheet alignment, resolving the contradiction between initial alignment precision and long-term alignment stability.
Solution Approach 2:
The gap distance between the first and second guide members is made variable rather than fixed. By allowing the first guide member to move and change its position parameter, the system compensates for roller hardness and diameter variations, maintaining reliable sheet alignment despite manufacturing tolerances in the rollers.
2Ease of repair
If the conveyance unit is made openable and closable for maintenance access, then ease of maintenance is improved, but the structural complexity increases
Solution Approach 1:
The conveyance unit is divided into separable components, with the first guide member being independently movable or removable from the second guide member. This segmentation allows maintenance personnel to access and service individual components without disassembling the entire apparatus, improving maintenance ease while keeping the overall structure relatively simple.
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 stabilizes the clearance between guide surfaces, preventing image defects by maintaining consistent sheet alignment and conveyance, even with variations in roller hardness and diameter, thus ensuring reliable image formation.
Implementation Method 1
The first guide is urged by a torsion spring in a direction approaching the second guide such that, with the conveyance unit disposed in the closed position, the distance between the first and second guide surfaces is restricted
Data Source
AI summary
An image forming apparatus includes a body, a conveyance unit, an image carrier, a transfer unit, and a pre-transfer guide. The body has a sheet passage for conveying sheets along inner and outer conveyance surfaces mutually facing. The conveyance unit includes the outer conveyance surface and is supported pivotably between an open position and a closed position relative to the inner conveyance surface. The transfer unit rotatably supports a transfer roller. The pre-transfer guide includes a first guide on the outer conveyance surface and a second guide on the inner conveyance surface. The first guide has a contact segment protruding toward the second guide. The first guide and the transfer unit are supported independently swingably relative to the transfer unit. The first guide is urged toward the second, and the distance between the two guide surfaces is restricted by the contact segment touching a contacted portion.