Transfer Unit Air Duct Segmentation for Heat Blocking and Stability
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Solution Overview
Problem
In image forming apparatuses with multiple housings, heat from a fixing unit accumulates downstream of the secondary transfer portion, affecting the intermediate transfer belt and causing image defects, and existing air duct configurations are prone to deformation due to unsupported ends.
Innovation Solution
An air duct is integrated with the transfer unit, including an air intake port, and moves with the transfer unit, supported at multiple points to prevent bending and effectively block heat from the fixing unit, using a configuration of three ducts to ensure stability and airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the air duct is fixed to the frame, then the air duct can be positioned to block heat from the fixing unit, but the unsupported end portion of the air duct bends towards the gravitational direction due to its own weight, causing deformation
Solution Approach 1:
The air duct is divided into multiple segments with intermediate support portions that can contact support rods. This segmentation allows the duct to be supported at multiple points along its length, preventing bending and deformation while maintaining its heat-blocking function.
Solution Approach 2:
Support rods are introduced as intermediary elements between the air duct and the frame. These support rods provide additional support points for the air duct, preventing it from bending under its own weight while allowing the duct to maintain its position for heat blocking.
2Ease of operation
If the transfer unit is designed to be pullable out for maintenance, then maintenance operability is improved, but the air duct cannot be supported near the opening on the front side of the frame, leading to bending and deformation
Solution Approach 1:
The air duct is segmented with intermediate support portions that can contact support rods positioned away from the front opening area. This allows the duct to be supported in regions where structural support is available, while still allowing the transfer unit to be pulled out for maintenance.
Solution Approach 2:
The support structure is extended into the depth dimension of the apparatus, with support rods positioned along the air duct's length rather than only at the front. This allows support to be provided in regions that do not interfere with the front opening needed for maintenance access.
3Object-affected harmful factors
If the air duct is made longer to extend further downstream to block heat, then heat blocking effectiveness is improved, but the unsupported end portion bends more due to increased length and weight
Solution Approach 1:
The extended air duct is divided into multiple segments with intermediate support portions positioned at regular intervals. This allows the duct to extend further downstream for better heat blocking while maintaining structural integrity through distributed support from multiple support rods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents image defects by blocking heat from the fixing unit, maintains duct stability, and enhances maintenance operability by preventing deformation and ensuring smooth user operations.
Implementation Method 1
an air duct located downstream of the secondary transfer nip portion in a conveyance direction of a recording material and below a portion of the transfer belt stretched between the secondary transfer inner roller and the stretching roller in the vertical direction
Data Source
AI summary
An image forming apparatus includes a photosensitive member, a transfer unit having a transfer belt, a primary transfer roller, a secondary transfer inner roller below the primary transfer roller in a vertical direction, and a stretching roller, a secondary transfer outer roller, a support unit, and an air duct provided in the transfer unit. The secondary transfer outer roller faces the secondary transfer inner roller via the transfer belt and forms a nip portion for secondarily transferring a toner image on the transfer belt to a sheet. The air duct is located downstream of the nip portion in a sheet conveyance direction and below a portion of the transfer belt stretched between the secondary transfer inner roller and the stretching roller in the vertical direction. The air duct includes an air intake port and moves with the transfer unit with movement of the transfer unit from the support unit.