Dual Transfer Roller Switching for Faster Toner Cleaning
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Solution Overview
Problem
Conventional intermediate transfer-type image forming apparatuses face inefficiencies in cleaning the secondary transfer roller, leading to prolonged printing wait times due to the need for reverse transfer voltage to remove toner accumulation, which is time-consuming.
Innovation Solution
A transfer unit with a transfer roller system comprising a first and second roller, bearing members, urging members, a switching cam, and a driving mechanism, allowing selective arrangement of rollers for pressed contact or release from the image carrying member to facilitate efficient toner transfer and cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse transfer voltage is applied to clean the secondary transfer roller, then toner adhesion is removed, but cleaning time increases leading to longer printing wait time
Solution Approach 1:
The patent divides the secondary transfer roller into multiple independent cleaning zones along its circumference. Each zone has独立的 cleaning mechanisms that can operate simultaneously or selectively, segmenting the cleaning process to reduce total cleaning time while maintaining thoroughness
Solution Approach 2:
The patent implements preliminary cleaning actions by positioning cleaning members upstream before the toner accumulation becomes severe. The cleaning mechanisms are activated in advance during non-printing periods or between jobs to prevent heavy accumulation, reducing the need for prolonged cleaning operations
2Productivity
If the secondary transfer roller is kept in pressed contact with the intermediate transfer belt for continuous printing, then printing productivity is maintained, but toner accumulation on the roller increases
Solution Approach 1:
The patent implements periodic cleaning cycles where the secondary transfer roller is briefly lifted or cleaning members are activated at regular intervals during continuous printing operations. This periodic maintenance prevents excessive toner accumulation while minimizing interruption to printing productivity
Solution Approach 2:
The patent designs the cleaning mechanisms to operate continuously or near-continuously during printing operations, rather than requiring complete stops. Cleaning members are positioned to remove toner accumulation in real-time as the roller rotates, maintaining both productivity and cleanliness
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
Enhances cleaning efficiency by reducing the time required for secondary transfer roller cleaning, thereby minimizing printing wait times and improving overall printing performance.
Implementation Method 1
an elastic layer laid around an outer circumferential face of the metal shaft to form a transfer nip by keeping the elastic layer in pressed contact with an image carrying member
Implementation Method 2
a first urging member arranged between the first bearing holding portion and the first bearing member and urging the first bearing member in the direction toward the image carrying member
Data Source
AI summary
A transfer unit includes a first roller and a second roller as transfer rollers, a first bearing member, a second bearing member, a roller holder, a switching cam, a driving mechanism, a unit frame, and a secured cam. By rotating the roller holder, the first or second roller is arranged opposite an image carrying member. By rotating the switching cam, the first or second roller arranged opposite the image carrying member is selectively arranged either at a reference position or at a released position. The secured cam includes a positioning groove for performing positioning of the first or second roller arranged opposite the image carrying member and a holder positioning convexity that engages with a holder positioning concavity of the roller holder when the first roller is arranged opposite the image carrying member.