Nested Shutter Mechanism for Drum Protection in Image Forming Units
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Solution Overview
Problem
In image forming apparatuses that use an electrophotographic method, there is a risk of reducing the service life of the image carrier and impairing the quality of printed images when the image forming unit, including the image carrier or photosensitive drum, is attached or detached, as users may accidentally touch the image carrier.
Innovation Solution
An image forming unit with a shutter unit that includes a first and second shutter member, pivotable about rotational axes, and a guiding and holding portion to protect the image carrier, allowing it to shift between closed and open states while preventing movement away from the image carrying surface, thus securing the image carrier and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the image forming unit is made compact, then the overall device size is reduced, but the space required for shutter movement increases
Solution Approach 1:
The shutter unit employs a nested structure where the second shutter member is disposed within the first shutter member. Both shutter members are pivotable about parallel rotational axes, allowing them to fold into each other during state transitions. This nesting arrangement minimizes the space swept during shifting while maintaining protection functionality, enabling compact device design without requiring excessive movement clearance.
2Device complexity
If the shutter unit structure is simplified, then device complexity is reduced, but the ability to prevent accidental contact is compromised
Solution Approach 1:
The shutter unit is segmented into multiple independent shutter members (first and second shutter members), each pivotable about its own rotational axis. This segmentation allows each member to independently perform the protection function, ensuring reliability even if one member fails or is improperly positioned. The segmented structure maintains robust protection capability while keeping each individual component simple in design.
Data Source
AI summary
An image forming unit includes an image carrier, a body, a shutter unit, a first guiding portion, and a holding portion. The body holds the image carrier with a portion of the image carrying surface being exposed. The shutter unit includes first and second shutter members. The first shutter member is held by the body, being pivotable about a first rotational axis relative to the body, and includes a first inner surface. The second shutter member is held by the first shutter member, being pivotable about a second rotational axis relative to the first shutter member, and includes a second inner surface and first and second contact portions. The shutter unit is shiftable between a closed state and an open state. The closed state is a state extended with the image carrying surface being covered. The open state is a state with the image carrying surface being exposed.