Intermediary Transfer Belt Roller Arrangement for Thick Paper
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Solution Overview
Problem
Image forming apparatuses using intermediary transfer belts face issues with toner transfer onto recording materials with surface unevenness, leading to impaired adhesive properties and electrostatic transfer, resulting in disturbances and white voids, especially with thick papers.
Innovation Solution
The apparatus includes a toner image forming portion, a movable endless belt, and a specific arrangement of rollers where the urging roller is positioned upstream and adjacent to the first roller, and the second roller is positioned downstream of the toner image forming portion, with defined geometric relationships between the rollers to maintain the belt's attitude and improve transfer properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a secondary transfer bias is applied to transfer toner image onto recording material, then transfer property is improved, but electric discharge occurs in gaps caused by surface unevenness, leading to charge removal or charge-up of toner and impaired electrostatic transfer property
Solution Approach 1:
The patent applies a preliminary pressing action upstream of the secondary transfer portion to flatten the recording material surface before toner transfer. This preliminary flattening prevents gap formation during the subsequent transfer process, eliminating the condition for electric discharge while maintaining the secondary transfer bias for effective toner transfer.
Solution Approach 2:
The patent introduces a pressing roller as an intermediary element between the recording material feed and the secondary transfer portion. This intermediary roller applies mechanical pressure to flatten the recording material surface upstream, acting as a mediator that prevents direct contact issues between the intermediary transfer belt and uneven recording material surfaces during transfer.
2Reliability
If the intermediary transfer belt is pressed against the recording material by the outer secondary transfer roller, then contact is improved, but vibration or waving of the belt occurs, causing unstable attitude and impaired adhesive property
Solution Approach 1:
The patent applies preliminary pressing upstream of the secondary transfer portion to stabilize the recording material surface before the belt contacts it. This preliminary action prevents vibration and waving by ensuring the recording material is flat and stable when the intermediary transfer belt makes contact, thereby maintaining stable belt attitude.
Solution Approach 2:
The patent provides beforehand cushioning by positioning the pressing roller upstream to preemptively flatten any surface unevenness or instability in the recording material before the intermediary transfer belt encounters it. This prior cushioning prevents vibration and waving that would otherwise occur during contact.
3Manufacturing precision
If the recording material is pressed against the intermediary transfer belt, then transfer contact is improved, but white voids and image defects occur at leading and trailing ends of thick papers
Solution Approach 1:
The patent applies preliminary pressing upstream of the secondary transfer portion to flatten thick recording materials before they reach the transfer zone. This preliminary action ensures uniform contact across the entire surface, including leading and trailing ends, preventing the formation of gaps that cause white voids and image defects during toner 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
This arrangement enhances the transfer property onto low smoothness papers and suppresses image defects at the leading and trailing ends of thick papers, ensuring consistent and clear toner images by minimizing electric discharge and maintaining close contact between the belt and recording material.
Implementation Method 1
a secondary transfer bias of an opposite polarity of a charge polarity of the toner is applied to the outer secondary transfer roller, so that the toner image is transferred from the intermediary transfer belt onto the recording material passing through the secondary transfer portion
Implementation Method 2
an urging roller which presses the recording material against the intermediary transfer belt upstream of and adjacent to the secondary transfer portion
Implementation Method 3
In the case where unevenness (projections and recesses) of several 10 μm or more exists on the surface of the recording material, at a recessed portion of the recording material, the intermediary transfer belt and the recording material cannot contact each other and a gap therebetween is formed
Data Source
AI summary
An image forming apparatus includes a toner image forming portion, an endless belt, first, second, and third rollers, and an urging roller, and satisfies: 25 (mm)>X>(R1+R2)2−(R1−R2)2)1/2−L1)+7 (mm), 3.5 (mm)≧Y>0.5 (mm), and L1>0 (mm). X is a distance between Lb passing through a rotation center of the third roller and perpendicular to an outer common tangential line L between the first and second rollers and Lc passing through a rotation center of the urging roller and L, R1 is a radius of the first roller, R2 is a radius of the urging roller, L1 is a distance between Lb and a line La passing through a rotation center of the first roller and L, and Y is a distance between L and a tangential line Ld of the urging roller parallel to L.