Pre-transfer charger periodic voltage control for white streak reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrophotographic image forming apparatuses with pre-transfer chargers fail to stabilize the charged state of toner images, leading to white streaks on paper due to residual toner adherence, making it difficult to detect when the pre-transfer charger is dirty.
Innovation Solution
An image forming apparatus with a pre-transfer charger and a control portion that applies and switches off voltage to form a cleaning assessment toner image, allowing for the detection of dirt by comparing images with and without voltage applied to the pre-transfer charger, and a cleaning mechanism using a rotating cleaning pad to efficiently clean the charger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage is continuously applied to the pre-transfer charger to stabilize the charged state of the toner image, then secondary transfer efficiency is improved, but residual toner adheres to the pre-transfer charger causing white streaks on paper
Solution Approach 1:
The pre-transfer charger operates in periodic cycles: applying voltage during image formation to stabilize charged state and improve secondary transfer efficiency, then stopping voltage application during cleaning assessment to detect residual toner adherence. This periodic switching resolves the contradiction by separating the conflicting requirements of continuous voltage application for efficiency versus voltage cessation to prevent white streaks.
2Object-generated harmful factors
If the pre-transfer charger is cleaned frequently to remove residual toner, then white streaks are reduced, but detection of dirt presence becomes difficult due to invisible white streaks
Solution Approach 1:
The invention creates a visual copy or representation of the invisible problem by forming a cleaning assessment toner image that makes residual toner adherence visible. When voltage is stopped and a toner image is formed, areas with residual toner appear as white streaks, providing a visible copy of the charger's contamination state that enables easy detection and monitoring.
3Difficulty of detecting and measuring
If voltage is stopped to detect residual toner, then cleaning assessment becomes possible, but secondary transfer efficiency decreases
Solution Approach 1:
The invention applies partial action by stopping voltage only for brief cleaning assessment periods rather than continuously. The voltage is applied during normal image formation for secondary transfer efficiency, then temporarily stopped only when cleaning assessment is needed. This partial cessation enables detection without significantly compromising overall transfer efficiency.
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
Effectively detects pre-transfer charger dirt and ensures efficient cleaning, minimizing white streaks and wear on cleaning components, thereby improving image transfer quality and maintenance efficiency.
Implementation Method 1
The pre-transfer charger applies applied voltage with a polarity opposite to a polarity of a charged toner image to the intermediate transfer element
Implementation Method 2
a cleaning mechanism using a rotating cleaning pad to efficiently clean the charger
Data Source
AI summary
An image forming apparatus is provided with an image bearing unit, an intermediate transfer unit, a primary transfer unit, a pre-transfer charger, and a control portion. The pre-transfer charger is located downstream of the primary transfer unit and upstream of the secondary transfer unit in a revolving direction, faces the outer peripheral surface of the intermediate transfer unit along a perpendicular direction perpendicular to the revolving direction, and charges the intermediate transfer unit when voltage is applied. The control portion, at time when determination is made as to the necessity of cleaning the pre-transfer charger, secondarily transfers a cleaning assessment toner image by switching between a state in which the voltage is applied to the pre-transfer charger and a state in which the voltage is not applied to the pre-transfer charger, the cleaning assessment toner image being in a uniform density.