Transfer Roller Switching Mechanism for Image Forming
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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 time-consuming process of applying a reverse transfer voltage to remove toner adhered to the roller.
Innovation Solution
A transfer unit with a first and second roller, each with an elastic layer, where the roller holder and switching cam mechanism allow for selective positioning of the rollers to form a transfer nip or release from the image carrying member, enabling efficient toner transfer and reducing the need for extensive cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a reverse transfer voltage is applied to clean the secondary transfer roller, then toner adherence is removed, but printing wait time increases
Solution Approach 1:
The patent applies preliminary action by performing cleaning of the secondary transfer roller during non-image forming periods before actual printing operations begin. The control unit proactively removes accumulated toner through reverse transfer voltage application, preventing toner adhesion issues before they affect printing quality or require interruptive cleaning during active printing operations.
Solution Approach 2:
The patent introduces an intermediary cleaning mechanism that uses a cleaning roller with cleaning elements (such as rubber or foam materials) to physically remove toner from the secondary transfer roller surface. This intermediary cleaning approach complements the electrical reverse transfer voltage method, providing a mechanical means to eliminate toner adherence without requiring prolonged voltage application that would extend printing wait time.
2Adaptability or versatility
If multiple secondary transfer rollers of different sizes are used, then adaptability to different recording medium widths is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamics by making the secondary transfer roller system adjustable and changeable during operation. The roller holder can pivot to select different rollers from the set, and the roller length can be adjusted to match different recording medium widths. This dynamic adaptability allows the system to respond to varying printing requirements without requiring a completely different device configuration for each medium size.
Solution Approach 2:
The patent applies segmentation by dividing the secondary transfer roller function into multiple discrete rollers of different lengths, each optimized for specific recording medium widths. Instead of using a single roller that must accommodate all sizes, the system segments the transfer function across multiple specialized rollers, with a roller holder that can selectively position the appropriate roller for each printing task, thereby achieving adaptability while managing complexity through modular design.
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 enhances productivity by minimizing printing wait times and improving image quality by allowing for efficient toner transfer and reduced toner adherence, while maintaining image processing efficiency.
Implementation Method 1
a transfer roller having a metal shaft and an elastic layer laid around a 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 a direction toward the image carrying member, and a second urging member arranged between the second bearing holding portion and the second bearing member and urging the second bearing member in a direction toward the image carrying member
Data Source
AI summary
A transfer unit includes, as transfer rollers, a first roller and a second roller of which the latter has an elastic layer larger in an axial direction than that of the former, a first bearing member, a second bearing member, a roller holder, a first urging member, a second urging member, a switching cam, a transfer voltage power supply, and a driving mechanism. By rotating the roller holder, one of the first and second rollers is arranged opposite an image carrying member and, by rotating the switching cam, the first or second roller arranged opposite the image carrying member is arranged either at a reference position at which, by being kept in pressed contact with the image carrying member, the first or second roller forms a transfer nip or at a released position at which the first or second roller lies away from the image carrying member.