Continuous Sheet Conveyance Control for Fixing Roller Thermal Expansion
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Solution Overview
Problem
Conventional image forming apparatuses face issues with slack or winding of continuous sheets due to misalignment of conveyance timings caused by thermal expansion of fixing members, particularly in electrophotographic processes, leading to abnormalities like noise and slip, especially with thicker sheets.
Innovation Solution
An image forming apparatus with a detection system to monitor the thermal expansion of fixing members, adjusting the driving control of both the fixing and downstream conveyance sections based on detected thermal expansion states to synchronize conveyance start and stop timings, preventing slack and slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fixing member is held in a separated state during non-printing to prevent damage to continuous sheet, then damage prevention is improved, but conveyance timing synchronization becomes difficult when printing starts
Solution Approach 1:
The control section performs preliminary action by detecting the thermal expansion state of the fixing member before printing starts, and pre-calculates the adjusted conveyance timing. This allows the system to be ready with the correct synchronization parameters when printing begins, resolving the contradiction between damage prevention during separation and timing synchronization at start-up.
Solution Approach 2:
The system uses feedback by continuously monitoring the thermal expansion state of the fixing member through detection sections (temperature sensors, displacement sensors) and adjusts the conveyance timing based on this feedback. This closed-loop control ensures both damage prevention and timing synchronization are maintained dynamically.
2Device complexity
If conventional fixed timing control is used without thermal expansion consideration, then control simplicity is maintained, but conveyance timing deviation occurs due to thermal expansion
Solution Approach 1:
The system changes the control parameter from fixed timing to dynamic timing adjustment based on thermal expansion detection. The control section modifies conveyance timing parameters (start timing, stop timing, nip width timing) according to the detected thermal expansion state, maintaining precision while managing complexity through automated detection and adjustment.
3Ease of operation
If downstream-side conveyance section operates independently with fixed timing, then operational independence is maintained, but slack occurs in continuous sheet when fixing member thermally expands
Solution Approach 1:
The system merges the control of the downstream-side conveyance section with the fixing section by making the downstream conveyance timing dependent on the detected thermal expansion state of the fixing member. This coordinated control ensures both sections work together to prevent slack, while the automatic detection system maintains ease of operation.
4Measurement precision
If multiple detection sections are added to monitor thermal expansion state, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The detection sections are designed with multi-functionality, serving both as temperature sensors and displacement sensors for thermal expansion detection. The control section integrates multiple detection functions into a unified control algorithm, reducing overall system complexity while maintaining high detection accuracy through versatile sensing components.
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 prevents slack and slip of continuous sheets by synchronizing conveyance timings, ensuring smooth and noise-free operation even with varying thermal expansion, particularly with thicker sheets.
Implementation Method 1
a detection section that detects a physical amount related to a thermal expansion state of a fixing member that forms the fixing nip
Implementation Method 2
heated and pressurized in a fixing section
Implementation Method 3
damage such as discoloration does not occur on the continuous sheet due to heat transmission from the fixing members
Data Source
AI summary
Provided is an image forming apparatus capable of printing on continuous sheet. The image forming apparatus includes: a fixing section that fixes an image on an unfixed surface of the continuous sheet while conveying the continuous sheet by a fixing nip; a downstream-side conveyance section that is disposed on a downstream side of the fixing section in a sheet conveyance direction and conveys the continuous sheet by a downstream-side conveyance nip; a detection section that detects a physical amount related to a thermal expansion state of a fixing member that forms the fixing nip; and a control section that controls driving aspects of the fixing section and the downstream-side conveyance section based on a detection result by the detection section.