Fixing Roller Speed Control for Loop Management
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Solution Overview
Problem
Conventional image forming apparatuses experience image quality degradation due to variations in recording material conveyance speed between the transfer and fixing roller pairs, leading to tension or excessive looping, which causes image blur and instability, particularly at the rear end of the recording material as it passes through the transfer portion.
Innovation Solution
An image forming apparatus with a controlling device that adjusts the recording material conveyance speed to maintain a loop within specific ranges, using multiple loop detecting sensors to switch between modes based on the recording material's size and position, ensuring stable loop levels and preventing rear end bounce.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the recording material conveyance speed of the fixing roller pair is increased to reduce loop level, then the loop level is reduced, but image quality degradation occurs due to tension on the recording material
Solution Approach 1:
The fixing roller pair dynamically adjusts its conveyance speed between two modes: a first speed to maintain loop level within a first range, and a second speed to reduce loop level to a second range. This dynamic speed adjustment prevents both excessive looping and tension-induced image degradation, resolving the contradiction between loop control and image quality.
Solution Approach 2:
The system changes the conveyance speed parameter of the fixing roller pair based on the position of the recording material. When the rear end approaches the transfer portion, the speed is switched from the first speed to the second speed, temporarily reducing the loop level to prevent bounce, then returning to the first speed after the rear end passes, thereby maintaining image quality while controlling loop dynamics.
2Shape
If the recording material conveyance speed of the fixing roller pair is decreased to maintain loop level, then the loop level is maintained, but image quality degradation occurs due to excessive looping and scraping
Solution Approach 1:
The system dynamically switches between two conveyance speeds of the fixing roller pair. The first speed maintains the loop within an acceptable range, while the second speed temporarily reduces the loop level to prevent excessive looping and scraping at critical moments, thereby resolving the contradiction between loop maintenance and image quality.
Solution Approach 2:
The system anticipates the potential problem of excessive looping and scraping by switching to the second speed before the rear end of the recording material reaches the transfer portion. This preliminary action prevents the harmful effect of excessive looping before it occurs, maintaining image quality while keeping the loop level controlled.
3Ease of operation
If a constant loop level is maintained throughout the process, then loop control is simplified, but image quality degradation occurs due to rear end bounce
Solution Approach 1:
The system implements dynamic loop control by switching between two conveyance speeds based on the position of the recording material. This dynamic approach maintains loop control simplicity while preventing rear end bounce, as the second speed is activated only when needed to reduce loop level before the rear end reaches the transfer portion, thereby resolving the contradiction between operational simplicity and image quality.
Solution Approach 2:
The system changes the conveyance speed parameter of the fixing roller pair based on the positional parameter of the recording material. When the rear end approaches the transfer portion, the speed parameter is switched from the first speed to the second speed, temporarily modifying the loop dynamics to prevent bounce, then returning to the original speed, thereby maintaining both operational simplicity and image quality.
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
The solution effectively suppresses image quality degradation by maintaining optimal loop levels and preventing rear end bouncing, ensuring consistent image formation across various recording material types and environmental conditions.
Implementation Method 1
The fixing roller pair 105 has been adapted to heat-fix the unfixed image onto the recording material
Implementation Method 2
a loop detecting sensor S for detecting a level of a loop of the recording material P has been disposed in the conveyance guide 120
Data Source
AI summary
An image forming apparatus includes a plurality of loop detecting sensors which detect various levels of loops formed on a recording material; and a controlling device which selects a specific one out of the loop sensors in accordance with information on the recording material, and then, switches a conveyance speed of a fixing roller pair in response to a detection signal output from the specific sensor, so as to control in such a manner as to keep the loop of the recording material within a constant range, the controlling device selecting the loop detecting sensor for detecting a loop of a level in accordance with the information on the recording material, so as to perform a loop keeping control for the recording material in response to the detection signal output from the selected loop detecting sensor.