Ejection Roller Cooling for Image Fixing
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Solution Overview
Problem
In image forming apparatuses using an electrophotographic system, the recent increase in printing speed leads to recording materials with toner images being stacked while still hot, causing toners to re-melt and stick together, resulting in image defects and missing portions when separated, and the demand for power-saving products further lowers toner melting points, exacerbating the issue.
Innovation Solution
An image forming apparatus with a pair of ejection rollers and a cooling unit that blows air onto the recording materials in a direction crossing their transport direction, positioned above the nip portion of the ejection rollers, to efficiently cool the materials after fixing, thereby preventing sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If recording materials are stacked in a stacking tray while temperatures are still high to increase printing speed, then productivity is improved, but toners re-melt and stick to sheet members causing image defects
Solution Approach 1:
The cooling unit is activated immediately after the fixing unit processes the recording material, performing preliminary cooling action before the material is stacked. This prevents toner re-melting by reducing temperature below the melting point before stacking occurs, resolving the contradiction between high-speed printing and image quality
Solution Approach 2:
Cooling air is introduced as an intermediary medium between the hot recording material and the stacking tray. The air flows across the surface of the recording material to transfer heat away, preventing direct contact between hot materials and avoiding toner re-melting while maintaining high productivity
2Temperature
If cooling air is blown onto recording materials by ejection rollers, then cooling efficiency is improved, but toner images are cooled unevenly causing contact marks
Solution Approach 1:
The cooling air is directed to blow onto specific regions of the recording material surface in a controlled manner. The air-blowing ports are positioned and angled to create localized cooling zones that avoid direct contact with toner image areas, ensuring uniform cooling without contact marks while maintaining efficient temperature reduction
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 solution effectively reduces the likelihood of toner re-melting and image defects by ensuring even cooling of the recording materials, maintaining image integrity and adhering to power-saving requirements.
Implementation Method 1
a cooling unit that cools the recording material ejected to the stacking unit by the pair of ejection rollers by blowing air onto the recording material
Data Source
AI summary
An image forming apparatus includes pair of ejection rollers that are used for ejecting a recording material to a stacking unit from a main body of the image forming apparatus and a cooling unit. The cooling unit includes, air-blowing ports that are used for blowing air onto the recording material in a direction crossing a transport direction of the recording material are positioned in a region that is located above the position of a nip portion of the pair of ejection rollers and below an extension line tangent to the nip portion of the pair of ejection rollers.