Cooling Unit for Toner Wax Adhesion Prevention
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Solution Overview
Problem
In image forming apparatuses, the wax in toner adheres to charging rollers, degrading their charging performance due to melting when the toner temperature exceeds the wax's crystallization temperature during conveyance.
Innovation Solution
An image forming apparatus with a cooling unit that blows air onto the paper sheet to lower the toner temperature to or below the wax's crystallization temperature, preventing wax adhesion on the charging rollers, and a control unit that adjusts the temperature based on sensed toner temperature and print coverage rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fixing unit heats the paper sheet to fix the toner, then the toner is fixed onto the paper sheet, but the wax in the toner melts and adheres to the charging roller
Solution Approach 1:
The cooling unit is positioned to cool the toner on the paper sheet before the paper sheet reaches the charging unit. This preliminary cooling action prevents the wax from melting and adhering to the charging roller, while still allowing the fixing unit to effectively fix the toner.
Solution Approach 2:
The cooling unit acts as an intermediary between the fixing unit and the charging unit. It temporarily reduces the toner temperature to prevent wax adhesion to the charging roller, while allowing the fixing process to complete effectively.
2Object-affected harmful factors
If the toner temperature is lowered to prevent wax adhesion, then the wax remains solid and does not adhere to the charging roller, but the fixing performance may be affected
Solution Approach 1:
The cooling unit performs preliminary cooling of the toner before it reaches the charging unit. This timing is critical - the toner is cooled just enough to prevent wax adhesion during conveyance, while the fixing unit can still effectively fix the toner before the cooling effect becomes excessive.
Solution Approach 2:
The system dynamically manages the toner temperature through the coordinated operation of the fixing unit and cooling unit. The fixing unit applies heat to fix the toner, while the cooling unit simultaneously manages the temperature to prevent wax adhesion, creating a dynamic temperature control system.
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 wax adhesion to charging rollers, maintaining charging performance and extending the life of the rollers by ensuring the wax remains solid, thus avoiding performance degradation.
Implementation Method 1
a cooling unit configured to cool the toner on the paper sheet
Implementation Method 2
the fixing unit heats and presses the paper sheet, to fix the toner onto the paper sheet
Implementation Method 3
the wax adheres to the charging roller electrically charged by the charging unit
Data Source
AI summary
An image forming apparatus includes: an image forming unit that forms an image by transferring toner onto a paper sheet; a fixing unit that fixes the image onto the paper sheet having the image formed thereon by the image forming unit; a charging unit that electrically charges the paper sheet having the image fixed thereonto by the fixing unit; and an adhesion preventing unit that prevents adhesion of wax to the charging unit, the wax being contained in the toner transferred onto the paper sheet, the adhesion preventing unit being located on an upstream side of the charging unit in a direction of conveyance of the paper sheet.