Removable Unit Upstream Projection for Positioning Accuracy
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Solution Overview
Problem
Existing removable units in image forming apparatuses, such as fixing devices, face challenges in maintaining positional accuracy and preventing damage when detached and placed on flat surfaces, leading to potential sheet jams and conveyability issues.
Innovation Solution
The proposed removable unit incorporates a positioning projection that projects downward to position units below it and an upstream projection that projects more downward than the positioning projection, ensuring the positioning projection remains non-contact with flat surfaces, thus preventing damage and maintaining accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the positioning projection is designed to project downward to position units below, then positioning accuracy is improved, but the positioning projection may contact flat surfaces when detached causing damage
Solution Approach 1:
The removable unit is segmented into multiple projection structures with different functions: the positioning projection (for accurate positioning) and the upstream projection (for surface contact protection). This segmentation allows each component to serve its specific purpose without interfering with the other, resolving the contradiction between positioning accuracy and damage prevention
Solution Approach 2:
The upstream projection acts as an intermediary element that contacts the flat surface first when the removable unit is detached, thereby protecting the positioning projection from direct contact and potential damage. This intermediary structure transfers the harmful contact function away from the critical positioning component
2Manufacturing precision
If the positioning projection projects downward for accurate positioning, then positioning function is improved, but deformation of the positioning projection may occur
Solution Approach 1:
By dividing the projection structure into positioning projection and upstream projection, the load and contact forces are distributed. The upstream projection absorbs external forces during handling, preventing these forces from being transmitted to the positioning projection, thus reducing deformation risk while maintaining positioning accuracy
Solution Approach 2:
The upstream projection serves as a protective buffer that absorbs potential impact or contact forces before they can reach the positioning projection. This beforehand cushioning effect prevents deformation of the critical positioning component during storage or handling
3Object-affected harmful factors
If the upstream projection projects more downward than the positioning projection, then protection of positioning projection is improved, but device complexity increases
Solution Approach 1:
Both projections are formed as integral parts of the same removable unit structure, using the same material and manufacturing process. This universal approach allows the simple addition of the upstream projection feature without significantly increasing overall device complexity, while providing effective protection
Solution Approach 2:
The upstream projection and positioning projection are merged into a single integrated structure on the removable unit. This combining approach minimizes the number of separate components and assembly steps, thereby limiting the increase in device complexity while still providing the protective function
Data Source
AI summary
A removable unit that is attachable to and detachable from a body of an apparatus includes a positioning projection and an upstream projection. The positioning projection projects downward to position a unit or a member located below the removable unit when the removable unit is attached to the body. The upstream projection projects more downward than the positioning projection at an upstream end of the removable unit in an attachment direction of the removable unit to the apparatus. A lower end of the positioning projection is located higher than a line connecting a lower end of the upstream projection and a lower portion of a downstream end of the removable unit in the attachment direction when viewed in a direction orthogonal to both an up and down direction and the attachment direction.