Fixing Roller Temperature Control for Condensation Slip
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Solution Overview
Problem
Image forming apparatuses using electrophotographic systems face issues with condensation slip due to steam generation when moist recording materials are heated, leading to reduced rotation speed, slipping, and increased print-out times, which degrade usability.
Innovation Solution
The apparatus includes a control system that adjusts the conveyance interval between recording materials based on the printing rate and environmental conditions, specifically delaying the conveyance of subsequent materials to allow the pressing roller's surface temperature to rise, preventing condensation slip by evaporating moisture, and using a film-heating system with a low heat capacity for quick warm-up and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressing roller surface temperature is increased to prevent condensation slip, then condensation slip is suppressed, but the first print-out time increases
Solution Approach 1:
The control portion performs preliminary heating of the pressing roller surface before actual printing starts. The warm-up time is extended specifically to heat the pressing roller surface to a temperature that prevents condensation, while the fixing apparatus is warmed up in parallel. This preliminary action ensures condensation slip is prevented from the first printed sheet without significantly increasing overall first print-out time.
Solution Approach 2:
The invention changes the temperature parameter of the pressing roller surface dynamically. During warm-up, the pressing roller is heated to a higher temperature than the minimum required for fixing, specifically to above the dew point to prevent condensation. This parameter change allows the surface to repel moisture and prevent condensation slip while maintaining efficient printing performance.
2Reliability
If the conveyance speed is reduced to allow pressing roller heating, then condensation slip is prevented, but printing productivity decreases
Solution Approach 1:
The control portion extends the warm-up time to perform preliminary heating of the pressing roller surface before high-speed printing begins. During this warm-up period, the conveyance speed is reduced or the apparatus is idle, allowing the pressing roller to reach the necessary temperature. Once warmed up, normal high-speed printing proceeds without condensation slip, maintaining productivity.
Solution Approach 2:
The invention implements periodic control of the conveyance mechanism during warm-up. The conveyance is performed in a periodic manner with extended intervals during the warm-up phase, allowing the pressing roller surface temperature to rise gradually. This periodic action pattern enables temperature increase without permanently reducing printing speed, thus preventing condensation while maintaining productivity during actual printing.
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 suppresses condensation slip, maintaining stable operation and reducing first print-out time, thereby enhancing usability and productivity while preventing defects like gloss unevenness, image rubbing, and paper folding.
Implementation Method 1
when a recording material having absorbed moisture is heated while being conveyed through the nip, steam is generated. As is known, when the steam causes condensation on a surface of the heating rotating member or the pressing rotating member
Implementation Method 2
a fixing portion that fixes the unfixed toner image on the recording material while heating and conveying the recording material
Data Source
AI summary
An acquisition portion acquires a rate of a size of a toner image being formed in a predetermined area on a recording material to a size of the predetermined area, in a consecutive print job, a control portion sets a longer conveyance interval between a preceding recording material and a subsequent recording material when the rate of the subsequent recording material exceeds a threshold than when the rate of the subsequent recording material does not exceed the threshold, and the predetermined area on a trailing end side of the recording material with respect to a center of the recording material in a recording material conveying direction is larger than the predetermined area on a leading end side of the recording material with respect to the center of the recording material, or the predetermined area is only on the trailing end side of the recording material.