Dynamic Guide Roller for Sheet Fluttering in Printers
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Solution Overview
Problem
In high-speed printers, sheet fluttering and vibration near the transfer nip cause image defects, and increasing sheet holding force to suppress fluttering leads to conveyance failures due to varying sheet stiffness.
Innovation Solution
An image forming apparatus with a pre-transfer guide mechanism featuring rotary members that adjust position based on sheet stiffness, using an urging force to guide sheets stably and reduce conveyance resistance, comprising a guide member, rotary members, and an urging portion to manage sheet orientation and conveyance for different sheet types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the force to hold the sheet is increased to suppress fluttering, then sheet stability is improved, but conveyance resistance increases causing conveyance failure
Solution Approach 1:
The guide roller is designed to rotate dynamically in response to sheet stiffness variations. When a stiff sheet is conveyed, the guide roller automatically rotates to reduce contact pressure and conveyance resistance. When a flexible sheet is conveyed, the guide roller maintains its position to provide sufficient holding force and suppress fluttering. This dynamic adjustment resolves the contradiction between sheet stability and conveyance resistance.
2Device complexity
If guide members are positioned away from transfer nip, then device complexity is reduced, but sheet control precision deteriorates causing fluttering
Solution Approach 1:
Instead of positioning guide members close to the transfer nip, the patent uses a dynamic guide roller that rotates to provide precise sheet control at a less critical location. The rotation of the guide roller creates a dynamic guiding effect that compensates for the increased distance from the transfer nip, maintaining sheet control precision without increasing device complexity.
Solution Approach 2:
The guide roller acts as an intermediary element that translates the motion of the conveyance roller to the sheet. By rotating in sync with the conveyance roller, it provides indirect but effective sheet control, serving as a mediator between the conveyance system and the sheet without requiring direct positioning near the transfer nip.
3Productivity
If high sheet conveyance speed is used, then productivity is improved, but image quality deteriorates due to sheet fluttering
Solution Approach 1:
The dynamic guide roller maintains optimal contact with sheets at high conveyance speeds, providing continuous stabilization without increasing conveyance resistance. This allows high-speed operation while preventing fluttering that would otherwise degrade image quality during transfer.
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 solution effectively suppresses sheet fluttering and conveyance failures across varying sheet stiffness, maintaining image quality and preventing excessive conveyance resistance, ensuring stable sheet conveyance and reduced image defects.
Implementation Method 1
an urging portion configured to urge the rotary member toward the first position, wherein an urging force of the urging portion is set such that the rotary member is positioned at the first position in a case where a first sheet having a first stiffness is conveyed
Implementation Method 2
a rotary member disposed to oppose the guide member and configured to be movable between a first position and a second position and rotate in accordance with the sheet conveyed by the conveyance portion
Data Source
AI summary
An image forming apparatus includes an image bearing member, a developing portion, a transfer member, a conveyance portion, a guide member disposed on the same side as the image bearing member with respect to a conveyance path, the guide member being configured to guide the sheet conveyed by the conveyance portion toward the transfer portion, a rotary member disposed to oppose the guide member and configured to be movable between a first position and a second position, and an urging portion. An urging force of the urging portion is set such that the rotary member is positioned at the first position in a case where a first sheet having a first stiffness is conveyed, and such that the rotary member is positioned at the second position by being pushed by a second sheet having a second stiffness.