Photosensitive Drum Exposure Pattern for Toner Slip Prevention
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Solution Overview
Problem
In new image forming apparatuses, the initial friction coefficient of the drum is high in low-temperature and low-humidity environments, leading to toner slipping through the cleaning member and causing faulty cleaning, resulting in image defects.
Innovation Solution
A control unit regulates toner supply by forming a toner supply pattern with varying exposure levels on the image bearing member, ensuring efficient toner distribution and effective cleaning by a cleaning member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a toner supply sequence is used to discharge toner to the drum in new-product process cartridges, then cleaning performance is improved, but toner may slip through the cleaning member causing faulty cleaning images
Solution Approach 1:
The patent applies local quality by creating different exposure regions (exposed and unexposed portions) on the photosensitive member surface. The unexposed portion receives no or reduced exposure, maintaining higher toner adhesion, while the exposed portion receives normal exposure for image formation. This spatial differentiation allows toner to be supplied to the cleaning contact portion without causing slip-through, resolving the contradiction between cleaning performance and image quality.
Solution Approach 2:
The patent segments the photosensitive member surface into distinct functional regions: a first region for normal image formation, a second region for toner supply with reduced exposure, and a third region as transition zone. This segmentation allows independent optimization of each region's function, enabling effective toner supply to the cleaning portion while preventing harmful toner slip-through that would cause faulty cleaning images.
2Reliability
If the amount of toner supply per unit area is high, then cleaning blocking layer formation is improved, but toner slip through the cleaning member increases
Solution Approach 1:
The patent changes the exposure parameter (light intensity or duration) in the unexposed portion to maintain higher toner adhesion without increasing toner supply amount. By reducing exposure in the second region, toner adheres more strongly to the photosensitive member surface, preventing slip-through while still allowing sufficient toner to reach the cleaning contact portion for blocking layer formation. This parameter modification resolves the contradiction between blocking layer formation and toner slip prevention.
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 prevents toner slipping and ensures stable cleaning performance, reducing image defects and improving print quality in new cartridges.
Implementation Method 1
an exposure unit configured to form an electrostatic latent image on a surface of the image bearing member by exposing the surface of the image bearing member
Implementation Method 2
a rotatable developer bearing member configured to, at a developing portion, supply toner to the surface of the image bearing member and develop the electrostatic latent image as a toner image
Implementation Method 3
a cleaning member configured to form a contact portion by coming into contact with the image bearing member and, at the contact portion, remove toner adhering to the surface of the image bearing member
Data Source
AI summary
A region of an image bearing member facing a developer bearing member at a developing portion is set as a first region, a region of the image bearing member facing the developer bearing member at the developing portion after a region of the developer bearing member facing the first region makes one revolution is set as a second region, and a region of the image bearing member between the first region and the second region is set as a third region. A first pattern for performing exposure and a second pattern for not performing exposure or for performing exposure with an exposure amount smaller than an exposure amount used for the first pattern is formed in the third region. A length of the second pattern is larger than a length of the first pattern in a rotational direction, and the first pattern and the second pattern are repetitively formed.