Image Forming Apparatus Toner Adhesion Control
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Solution Overview
Problem
Existing image forming apparatuses face issues with adhesion between stacked recording sheets due to high-temperature toner, leading to defects in fixed images, and existing solutions do not adequately consider the toner application amount, resulting in potential productivity deterioration.
Innovation Solution
An image forming apparatus that includes a controller to adjust the number of image formations per unit time based on the maximum toner application amount per unit area, reducing throughput when high toner application is detected to prevent adhesion and maintain productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fixing temperature is increased and conveyance interval is reduced to fix toner instantaneously, then the image forming speed is improved, but the recording sheets maintain high temperature on the sheet discharge unit causing toner adhesion between stacked sheets
Solution Approach 1:
The patent applies dynamics by making the conveyance interval variable rather than fixed. The control unit dynamically adjusts the conveyance interval based on the toner application amount detected for each sheet. When toner application amount is large, the conveyance interval is increased to allow cooling; when toner application amount is small, the conveyance interval is reduced to maintain high productivity. This dynamic adjustment resolves the contradiction between maintaining high image forming speed and preventing toner adhesion.
2Reliability
If the conveyance interval is increased to allow cooling of recording sheets, then adhesion between stacked sheets is prevented, but the image forming speed is reduced
Solution Approach 1:
The patent applies local quality by differentiating the conveyance interval adjustment based on local characteristics of each sheet's toner application amount. Instead of uniformly increasing the conveyance interval for all sheets (which would reduce overall productivity), the control unit selectively increases the interval only for sheets with large toner application amounts that are at risk of adhesion. Sheets with small toner application amounts maintain the original fast conveyance interval, thus preserving image forming speed while preventing adhesion where necessary.
3Reliability
If cooling mechanisms are added to cool recording sheets on the sheet discharge unit, then adhesion between stacked sheets is prevented, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical cooling mechanism (such as cooling rollers or fans) with a control-based solution. Instead of adding physical cooling devices to the sheet discharge unit, the system uses the control unit to dynamically adjust the conveyance interval based on toner application amount detection. This substitution eliminates the need for additional cooling hardware, maintaining adhesion prevention effectiveness while avoiding increased device complexity.
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 adhesion between stacked recording sheets while maintaining productivity by dynamically controlling image formation rates based on toner application amounts, ensuring effective throughput and image quality.
Implementation Method 1
a fixing unit configured to heat and fix the toner image formed on the sheet
Implementation Method 2
If the fixed toner is maintained at a high temperature and the temperature of the toner reaches a toner softening point or higher, the toner fixed onto each recording sheet once is softened again
Data Source
AI summary
An image forming apparatus includes an image forming unit, a fixing unit, a sheet discharge unit to stack sheets, an acquisition unit, and a controller. The fixing unit fixes a toner image formed on a sheet by the image forming unit. The acquisition unit acquires information corresponding to a maximum toner application amount per unit area of the formed toner image. The controller controls the number of image formations on the sheets per unit time based on the acquired information. The controller executes a first job with a first number of image formations on the sheets per unit time during a period from an Lth sheet to an Mth sheet in the first job, and executes a second job with a second and smaller number of image formations on the sheets per unit time during the period from the Lth to the Mth sheet in the second job.