Transfer Unit Positioning for Image Forming Apparatus
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Solution Overview
Problem
Conventional image forming apparatuses with intermediate transfer belts face issues in precise positioning of transfer units due to fit tolerance in the vertical direction, leading to potential image defects during image formation.
Innovation Solution
The apparatus includes a transfer unit with an endless belt, stretching members, a primary transfer member, and a positioning unit with abutting faces arranged to intersect the conveyance direction, allowing precise positioning by urging the secondary transfer member towards a facing member, which maintains the transfer unit's position despite vertical forces from the transfer material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fit tolerance is provided between guiding rail and guiding pin for easy attachment, then ease of operation is improved, but positioning precision deteriorates causing image defects
Solution Approach 1:
The invention introduces a new dimension for positioning by arranging abutting faces in the conveyance direction (vertical direction) rather than relying solely on horizontal guiding rail-pin fit. The first and second abutting faces extend in the belt width direction and are arranged at different positions in the conveyance direction, creating a multi-dimensional positioning system that prevents shifting while maintaining ease of attachment.
Solution Approach 2:
The abutting faces are designed to receive urging force from the urging member in advance, positioning the transfer unit before image formation occurs. The first abutting face positions the transfer unit in the conveyance direction, and the second abutting face positions it in the opposite direction, pre-establishing precise positioning to prevent any shifting during subsequent image formation operations.
2Stability of the object's composition
If urging force is applied to maintain positioning, then positioning stability is improved, but device complexity increases due to additional urging member
Solution Approach 1:
The urging member serves multiple functions: it applies urging force to the transfer unit through the secondary transfer member, and simultaneously this urging force positions the transfer unit against the abutting faces. The abutting faces themselves serve dual purposes as both positioning elements and reaction surfaces for the urging force, reducing the need for separate positioning and stabilization mechanisms.
Data Source
AI summary
An image forming apparatus includes an image bearing member that bears a toner image, a transfer unit having an endless belt, a positioning unit that positions the transfer unit, and a secondary transfer member. The secondary transfer member is in touch with the endless belt to form a secondary transfer portion. When the toner image is transferred to the endless belt from the image bearing member, the secondary transfer member transfers the toner image from the endless belt at the secondary transfer portion to a transfer material. The positioning unit includes a first abutting face to position the transfer unit in a conveyance direction and a second abutting face to position the transfer unit in a direction opposite to the conveyance direction. An attaching/detaching direction of the transfer unit is a direction intersecting with a surface of the transfer material to which the toner image is transferred.