Variable Section Duct for Optical Scanner Cooling
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Solution Overview
Problem
In optical scanning devices of image forming apparatuses, the heat generated by the rotating polygon mirror and its motor causes thermal deformation of the housing and optical components, leading to poor image formation due to increased temperature.
Innovation Solution
An image forming apparatus with an optical scanning device, a duct, and a cooling fan, where the duct is designed with a gradually decreasing sectional area to enhance airflow speed and contact with the rotating shaft of the polygon motor, and a cooling fan generates airflow to efficiently cool the motor and reduce internal temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional duct with uniform sectional area is used, then the structure is simple, but the airflow speed is insufficient and cooling efficiency is low
Solution Approach 1:
The duct's sectional area parameter is changed along the flow direction, transitioning from uniform to variable cross-section. The duct includes a first portion with a first sectional area and a second portion with a second sectional area that is smaller than the first, creating a gradual contraction that accelerates airflow and improves cooling efficiency without excessive structural complexity
Solution Approach 2:
The duct design creates dynamic airflow characteristics by varying the sectional area along the flow direction. This variable geometry causes the airflow to accelerate through the contracting section, optimizing the cooling effect on the rotating shaft while maintaining reasonable structural simplicity
2Temperature
If the duct sectional area is reduced to increase airflow speed, then cooling efficiency improves, but the duct becomes more complex
Solution Approach 1:
The duct's sectional area parameter is optimized to reduce the temperature of the rotating shaft. The duct includes a first portion with a first sectional area and a second portion with a second sectional area that is smaller than the first, creating a gradual contraction that accelerates airflow and improves cooling efficiency without excessive structural complexity
Solution Approach 2:
The duct has different sectional areas at different locations along the flow direction. The first portion has a larger sectional area for gentle airflow introduction, while the second portion has a smaller sectional area to accelerate airflow near the rotating shaft, creating locally optimized cooling zones
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
The solution effectively suppresses temperature increases within the optical scanning device, preventing thermal deformation and ensuring high-quality image formation by efficiently cooling the rotating shaft and surrounding components.
Implementation Method 1
The cooling fan generates airflow that flows inside the duct
Implementation Method 2
A sectional area of the duct becomes gradually small toward the part of the rotating shaft exposed into the duct from an upstream side of the part of the rotating shaft exposed into the duct with respect to the flow direction of the airflow in the duct
Data Source
AI summary
An image forming apparatus includes an optical scanning device, a duct, and a cooling fan. The optical scanning device has a rotating polygon mirror, a motor which has a rotating shaft fixed to the rotating polygon mirror, and a housing that accommodates the rotating polygon mirror and the motor. The duct is disposed adjacent to the optical scanning device, and a part of the rotating shaft is exposed into the duct. The cooling fan generates airflow inside the duct. A sectional area of the duct becomes gradually small toward the part of the rotating shaft exposed into the duct from an upstream side of the part of the rotating shaft exposed into the duct with respect to a flow direction of the airflow in the duct, and a sectional area of the duct becomes large at a downstream side of the part of the rotating shaft exposed into the duct.