Ejection Roller Conveyance Control for Image Fixing Apparatus
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Solution Overview
Problem
Image forming apparatuses using long printing objects face challenges in stabilizing the conveyance of the printing object when the rollers of the fixing device separate, leading to potential spoilage and meandering, especially during warm-down and warm-up processes.
Innovation Solution
The apparatus includes a transfer device, a fixing device with selectable nip pressure, and an ejection device, allowing for adjustable nip pressures and conveying forces to maintain stable conveyance even when the fixing device's rollers are separated, by increasing the conveying force of the ejection rollers during non-fixing and non-transfer states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the pair of fixing rollers is separated from each other during warm-down to prevent reduction in life, then the life of the fixing rollers is improved, but the stable conveyance of the printing object deteriorates due to loss of nip pressure
Solution Approach 1:
The invention changes the parameter of nip pressure in the ejection device based on the operational state of the fixing device. During warm-down when fixing rollers are separated, the ejection device increases its nip pressure to compensate for the loss of conveying force, thereby maintaining stable printing object conveyance while allowing the fixing rollers to separate for their protection.
2Manufacturing precision
If high nip pressure is applied to the fixing device to fix toner image, then the image fixing quality is improved, but the conveying stability of other rollers deteriorates due to unbalanced nip pressures
Solution Approach 1:
The invention dynamically adjusts the nip pressure parameter of the ejection device based on the operational state of the fixing device. When the fixing device applies high nip pressure for image fixing, the ejection device reduces its nip pressure to maintain balance. When the fixing device separates rollers during warm-down, the ejection device increases its nip pressure to compensate, thereby maintaining conveying stability across different operational phases.
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 ensures stable conveyance of the printing object, preventing slip and damage, while minimizing heat transmission and maintaining image quality by adjusting nip pressures and conveying forces based on the thickness of the printing material.
Implementation Method 1
A high nip pressure is applied at high temperature to the pair of rollers, due to the need to fix the unfixed toner image onto the printing object
Implementation Method 2
a tension adjustment device disposed upstream of the transfer device in the direction in which the printing object is conveyed, the tension adjustment device applying a prescribed tension to the printing object
Implementation Method 3
a transfer device including a pair of transfer rollers forming a transfer nip that transfers an unfixed toner image onto the printing object
Data Source
AI summary
In an image forming apparatus, when a fixing device is in a non-fixing state and a transfer device is in a non-transfer state, an ejection device increases a conveying force by a pair of ejection rollers as compared to the conveying force in the fixing state. According to this image forming apparatus, a printing object can be stably conveyed even when a pair of rollers of the fixing device becomes separated from each other.