Brush Member Potential Control for Image Defect Reduction
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Solution Overview
Problem
In image forming apparatuses using cleanerless methods, paper dust on the drum can cause image defects due to the brush's inability to effectively hold and manage dust during changes in drum speed, leading to dust falling back onto the drum surface.
Innovation Solution
An image forming apparatus with a brush member that forms a contact portion downstream of the transfer portion and upstream of the charging portion, where a control unit manages the driving state to transition from a first potential difference to a second potential difference with the same polarity but lesser absolute value, ensuring stable paper dust collection and reduced image defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixed brush is disposed to contact the drum downstream of the transfer portion and upstream of the charging portion, then paper dust can be collected on the drum, but paper dust held in the brush can fall back onto the drum surface due to speed changes during starting and stopping, causing image defects
Solution Approach 1:
The patent extracts the harmful paper dust from the drum surface by introducing a brush member that contacts and collects the dust. The brush is positioned downstream of the transfer portion and upstream of the charging portion to remove paper dust before it can cause image defects, effectively separating the dust collection function from the main image formation process.
Solution Approach 2:
The patent applies dynamics by making the brush member rotatable rather than fixed. The brush rotation speed is controlled to match the drum surface speed during operation, ensuring effective dust collection. During starting and stopping, the brush rotation is independently controlled to prevent paper dust from falling back onto the drum, thus maintaining image quality while continuously removing paper dust.
2Productivity
If the brush rotates at the same speed as the drum during starting and stopping, then paper dust collection is effective, but paper dust held in the brush falls back onto the drum due to speed changes, causing image defects
Solution Approach 1:
The patent implements dynamic speed control of the brush member. During normal operation, the brush rotates at the same speed as the drum surface for effective dust collection. During starting and stopping phases, the brush rotation speed is independently adjusted to prevent paper dust from falling back onto the drum, thus maintaining both collection efficiency and preventing harmful dust redistribution.
Solution Approach 2:
The patent employs feedback control by detecting the drum surface speed and adjusting the brush rotation speed accordingly. This ensures the brush maintains optimal relative speed with the drum surface during operation while preventing dust fallout during speed transitions, automatically adapting to operational conditions to maintain image quality.
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
The solution effectively stabilizes paper dust collection in the brush, reducing image defects caused by dust falling back onto the drum, as demonstrated by a significant reduction in blot images during sheet passage tests.
Implementation Method 1
a contact portion between the brush member and the photosensitive drum, downstream of the transfer portion and upstream of the charging portion in the rotation direction of the photosensitive drum
Data Source
AI summary
A driving unit is controlled so that a driving state where an image bearing member is driven with a first potential difference formed between a brush member and the image bearing member at a contact portion where the image bearing member is in contact with the brush member transitions to a stopped state where the image bearing member stops being driven with a second potential difference formed, the second potential difference having an absolute value less than that of the first potential difference.