Developing Roller Preliminary Rotation for Density Uniformity
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Solution Overview
Problem
Image forming apparatuses using electrophotography face issues with uneven density due to strain on elastic developing rollers, leading to irregular wear and potential friction problems during rotation.
Innovation Solution
Incorporating a preliminary rotation mechanism for the developing and carrying rollers, separated from the cleaning member, to eliminate strain and reduce wear by rotating them before main image formation, thereby preventing friction and ensuring uniform developer distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the developing roller is kept in pressure contact with the cleaning blade during standby, then the roller remains stationary and clean, but strain accumulates on the roller surface causing uneven density during subsequent rotation
Solution Approach 1:
The developing roller is rotated at a preliminary stage before image formation to eliminate strain that would otherwise accumulate during standby. This preliminary rotation action prevents the strain-induced uneven density problem that would occur if the roller remained stationary in pressure contact with the cleaning blade.
2Reliability
If the developing roller is rotated during standby to eliminate strain, then image density uniformity is improved, but friction with the cleaning blade increases causing irregular wear
Solution Approach 1:
The system dynamically adjusts the contact state between the developing roller and cleaning blade based on operational phase. During preliminary rotation, the roller rotates without pressure contact to eliminate strain. During subsequent image formation, the roller returns to pressure contact with the cleaning blade for normal operation. This dynamic switching prevents wear while maintaining density uniformity.
3Reliability
If the developing roller rotates without developer adhesion, then strain is eliminated, but abnormal friction occurs with the cleaning blade
Solution Approach 1:
The rotation to eliminate strain is performed as a preliminary action before the cleaning blade is positioned for contact. By completing the strain-elimination rotation first, then subsequently establishing pressure contact with the cleaning blade, the system avoids abnormal friction that would occur if rotation happened without proper developer adhesion conditions.
Data Source
AI summary
An image forming apparatus includes: a development member carrying developer for forming a toner image on an image carrier; a cleaning member in contact with the development member for removing the developer left on the development member; a carrying member provided in contact with the development member, for carrying the supplied developer to the development member; a driving part driving at least one of the carrying member and the development member; and a regulating mechanism for separating the cleaning member and the development member from each other. The driving part causes preliminary rotation of the development member and the carrying member with the cleaning member separated from the development member, before starting main rotation for image formation.