Exposure Window Geometry for Image Forming Apparatus Airflow Control
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Solution Overview
Problem
Conventional image forming apparatuses experience a decrease in electric charge efficiency due to airflow counter to the ion flow generated during charging, caused by the operation of the exhaust fan drawing air between the scanner unit and the process unit.
Innovation Solution
The image forming apparatus is designed with an exposure window defined by walls where the distance between the farthest wall from the charger and the exposure device is greater than the distance between the nearest wall from the charger, ensuring higher airflow velocity through the first wall area, thus restricting air flow into the process unit and preventing counter airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the exhaust fan draws air between the scanner unit and the process unit, then heat discharge efficiency is improved, but electric charge efficiency deteriorates due to counter airflow
Solution Approach 1:
The exposure window is segmented into multiple regions (first region and second region) separated by a partition wall, allowing independent control of airflow in each region. The first region handles exhaust airflow while the second region protects the charging area, resolving the contradiction between heat discharge and charge efficiency
Solution Approach 2:
A partition wall is introduced as an intermediary structure within the exposure window to separate the exhaust air flow path from the charging area. This mediator allows the exhaust fan to operate efficiently while preventing counter airflow from reaching the photosensitive element during charging
2Ease of operation
If the exhaust fan operates to ventilate the apparatus, then air circulation is improved, but ion flow direction is reversed causing charge efficiency loss
Solution Approach 1:
Different regions within the exposure window are assigned different functions: the first region allows free air circulation for ventilation, while the second region maintains controlled conditions for efficient charging. This local differentiation resolves the contradiction between overall air circulation and localized charge efficiency
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
This configuration restricts the amount of air flowing into the process unit, preventing a decrease in electric charge efficiency and ensuring a smooth ion flow, as demonstrated by experimental results where the ratio of distances A/B < 0.8 effectively directs airflow away from the charger, maintaining charge efficiency.
Implementation Method 1
ion flow generated during the electric charge by the charger (i.e., airflow generated by the movement of ions upon electric charge) and directed from the charger to the photosensitive drum
Implementation Method 2
Air between the scanner unit and the process unit is drawn by the exhaust fan from the exposure window toward the charger so as to perform a heat discharging operation
Data Source
AI summary
An image forming apparatus includes: a photosensitive element; a charger for electrically charging the photosensitive element; an exposure device for scanning laser light across the photosensitive element that has been electrically charged by the charger; an exposure window positioned away from the exposure device for a predetermined distance and through which the laser light passes; and an exhaust fan for drawing air between the exposure device and the exposure window toward the charger and discharging the air from the image forming apparatus. The exposure window is defined by a plurality of walls, in which a first wall that is the farthest wall from the charger and a second wall that is the nearest wall from the charger satisfy a formula: A<B, where A is a distance between the first wall and the exposure device, and B is a distance between the second wall and the exposure device.