Image Forming Apparatus Roller Offset Adjustment
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Solution Overview
Problem
Conventional image forming apparatuses experience leading end misregistration due to changes in offset amount, which affects the positioning of the toner image on the recording material, particularly when handling varying types of paper with different rigidities, leading to issues like paper jams and image defects.
Innovation Solution
The image forming apparatus adjusts the relative position between the inner and outer rollers of the secondary transfer nip based on the basis weight of the recording material, changing the offset amount to maintain optimal image registration by synchronizing the feeding start timing of the recording material with the image writing timing, thereby correcting deviations caused by changes in offset positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the offset amount is changed to improve separation property and suppress image defects, then the transfer property is improved, but leading end misregistration occurs
Solution Approach 1:
The patent applies dynamics by making the offset amount adjustable rather than fixed. The position changing mechanism allows the relative position between the inner roller and outer roller to be dynamically changed between a first relative position (first offset amount) and a second relative position (second offset amount), enabling the system to adapt to different recording material conditions while maintaining proper image registration.
Solution Approach 2:
The patent changes the offset amount parameter between two specific values depending on the recording material type. By switching between the first offset amount (for thin paper) and the second offset amount (for thick paper), the system optimizes transfer property for each material type without causing leading end misregistration, as each offset amount is specifically designed to work with its corresponding paper type.
2Device complexity
If a fixed secondary transfer portion position is used, then device complexity is reduced, but it cannot handle diverse recording materials effectively
Solution Approach 1:
The patent introduces a position changing mechanism that enables the secondary transfer portion to dynamically adjust its position by changing the offset amount between two predetermined values. This dynamic adjustment capability allows the apparatus to handle diverse recording materials (thin paper and thick paper) effectively while maintaining reasonable device complexity through the use of a relatively simple two-position adjustment system.
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 approach effectively suppresses leading end misregistration and improves the transfer property of toner images onto diverse types of paper, ensuring consistent image quality across different paper rigidities by dynamically adjusting the offset amount and registration timing.
Implementation Method 1
a secondary transfer voltage of a polarity opposite to a charge polarity of toner is applied to the outer roller (or a voltage of the same polarity as the charge polarity of the toner is applied to the inner roller), so that the toner image is secondary-transferred from the intermediary transfer belt onto the recording material in the secondary transfer portion
Data Source
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AI summary
An image forming apparatus includes an image bearing member, an image forming portion, an endless belt, a plurality of stretching rollers including an inner roller, an outer roller, a position changing mechanism capable of changing a position of the inner roller to a first position and a second position positioned downstream of the first position with respect to a rotational direction of the endless belt, a feeding member, a feeding member driving portion, and a controller. A feeding start timing of a recording material by the feeding member depends on the position of the inner roller during transfer of a toner image onto the recording material.