Secondary Transfer Current Control for Image Forming Apparatus
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Solution Overview
Problem
The design of image forming apparatuses faces challenges in securing a creepage distance and wiring space near the secondary transfer roller due to high transfer voltages and limited space, complicating the output of secondary transfer current, especially when compared to configurations where the first belt support roller is not grounded.
Innovation Solution
An image forming apparatus with a current output portion connected to the first belt support roller, which passes the secondary transfer current across the secondary transfer roller, and a control portion that senses leakage current to set the output current, maintaining the voltage on the second belt support roller within a specific range to prevent toner movement and ensure efficient secondary transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary transfer roller is connected to the ground and high transfer voltage is applied, then secondary transfer current can be output, but it becomes difficult to secure creepage distance and wiring space near the side face of the housing
Solution Approach 1:
The first belt support roller serves as an intermediary component that receives the output current from the current output portion and transmits it to the intermediate transfer belt. This mediator approach allows the high voltage to be applied at a location (first belt support roller) where wiring space and creepage distance can be easily secured, while still achieving the desired secondary transfer function through the intermediate transfer belt system
2Device complexity
If the first belt support roller is not connected to ground, then wiring space and creepage distance can be easily secured, but the roller may accumulate static charge affecting transfer stability
Solution Approach 1:
The invention changes the electrical parameter configuration by connecting the first belt support roller to the output current rather than ground, and by controlling the voltage potential of the second belt support roller within a specific range (-50V to +50V). This parameter change allows the system to maintain transfer stability while simplifying the wiring design and securing adequate creepage distance
3Ease of manufacture
If the voltage on the second belt support roller is not controlled, then the system is simpler to design, but toner may move to peripheral members causing image defects
Solution Approach 1:
The invention implements feedback control by monitoring and adjusting the voltage potential of the second belt support roller to maintain it within the range of -50V to +50V. This feedback mechanism prevents toner from moving to peripheral members by ensuring the electric field conditions do not favor toner migration, while keeping the overall system design relatively simple through standardized voltage control
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 allows for a consistent secondary transfer current while minimizing toner attachment to peripheral members, reducing image defects and simplifying the design by maintaining the voltage on the belt support roller within a controlled range, thus preventing toner movement and ensuring reliable image transfer.
Implementation Method 1
Applying to the primary transfer roller a primary transfer voltage having a polarity opposite to that of toner permits the toner image carried on the photosensitive drum to be primarily transferred to the intermediate transfer belt
Implementation Method 2
The secondary transfer roller secondarily transfers, with a secondary transfer current, the toner image primarily transferred to the intermediate transfer belt further to a sheet passing between the secondary transfer roller and the intermediate transfer belt
Implementation Method 3
The first belt support roller is in contact with the inner circumferential face of the intermediate transfer belt such that the intermediate transfer belt is stretched around the first belt support roller
Data Source
AI summary
An image forming apparatus includes an image carrying member, an intermediate transfer belt, a primary transfer roller, a first belt support roller, a secondary transfer roller, a second belt support roller, a current output portion, a current sensing portion, and a control portion. The current output portion passes across the secondary transfer roller a secondary transfer current as part of an output current. The current output portion and the second belt support roller are electrically connected together. The current sensing portion senses a leakage current passing from the first belt support roller via the intermediate transfer belt to the second belt support roller. The control portion sets the output current such that the secondary transfer current has a value given by subtracting a leakage current from the output current and keeps the voltage on the second belt support roller between −50 V and 50 V, inclusive.