Developing Unit Positioning for Twin Sleeve Gap Errors
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Solution Overview
Problem
Conventional image forming apparatuses experience SD gap errors due to alignment errors between twin sleeves, leading to uneven contact pressures and deformation, resulting in image defects such as density non-uniformity.
Innovation Solution
The image forming apparatus employs a developing device with positioning blocks and urging units to ensure precise alignment and equal contact pressures between the sleeves and the photosensitive drum, using elongated circular holes and spherical positioning pins to regulate the relative position and rotation of the developing device, thereby minimizing the impact of alignment errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If abutting rollers are provided at both ends of two or more developing sleeves and urged toward the drum, then the SD gap can be regulated, but alignment errors between twin sleeves cause unequal contact pressures and deformation
Solution Approach 1:
The developing device is designed to be movable relative to the drum, allowing dynamic adjustment of the position and orientation of the developing sleeves. This enables the system to adapt to alignment errors by shifting the entire developing device, thereby equalizing the contact pressures of the abutting rollers on the drum surface.
Solution Approach 2:
The developing device automatically adjusts its own position and orientation through the movable configuration, without requiring external intervention. The system self-corrects alignment errors by allowing the developing sleeves to shift relative to the drum, ensuring uniform contact pressures are achieved naturally during operation.
2Device complexity
If the developing device is fixed relative to the drum, then the structure is simple, but alignment errors cannot be compensated, leading to SD gap variations
Solution Approach 1:
The developing device transitions from a fixed configuration to a movable one, enabling dynamic compensation for alignment errors. The movable design allows the developing sleeves to adjust their position relative to the drum, maintaining uniform SD gaps despite manufacturing tolerances in the drum or sleeve alignment.
Data Source
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AI summary
An image forming apparatus includes an image forming unit for supporting an image bearing member; a developing unit including a first developer carrying member and a second developer carrying member; a first gap regulating member for regulating a gap between the image bearing member and the first developer carrying member; a second gap regulating member for regulating a gap between the image bearing member and the second developer carrying member; an urging member for urging the developing unit toward the image forming unit so that the first gap regulating member and the second gap regulating member are urged against an abutment portion provided on the image bearing member; and a positioning member for positioning the developing unit relative to the image forming unit. The positioning member includes a preventing portion for preventing, while permitting movement of the developing unit in a circumferential direction of the image bearing member at one longitudinal end of the developing unit, movement of the developing unit in the circumferential direction of the image bearing member at the other longitudinal end of the developing unit.