Adjustable Separation Members for Thermal Expansion in Fixing Devices
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Solution Overview
Problem
Existing fixing devices in electrophotographic image forming apparatuses face challenges in maintaining a constant separation gap between the heating rotator and separation members, leading to sheet jams when handling sheets of varying sizes due to temperature unevenness and thermal expansion, as the positions of separation members cannot be individually adjusted.
Innovation Solution
A fixing device with adjustable separation members, where the positions of multiple separation members are individually adjusted using an adjustor to maintain equal distances and account for varying sheet sizes and thermal expansion, incorporating distance sensors and drivers to ensure consistent separation gaps, and temperature sensors to adjust based on surface temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separation gap is made large, then the sheet can easily pass through without being caught, but the sheet may enter the separation gap and cause a sheet jam
Solution Approach 1:
The patent applies local quality by making each separation member independently adjustable, allowing different separation members to have different positions relative to the heating rotator. This enables the separation gap to be optimized at each local position according to the thermal expansion characteristics at that specific location, preventing sheet jams while maintaining reliable separation.
Solution Approach 2:
The patent implements dynamics by making the separation members adjustable rather than fixed. The positions of separation members can be changed to adapt to the thermal expansion of the heating rotator when sheets of various sizes pass through, allowing the separation gap to be dynamically optimized to prevent both sheet entry into the gap and sheet catching.
2Measurement precision
If the separation gap is made small, then the separation precision is improved, but the separation member comes into contact with the heating rotator when thermally expanded, causing damage
Solution Approach 1:
The patent applies local quality by allowing each separation member to be independently positioned based on the local thermal expansion characteristics of the heating rotator. This enables precise control of the separation gap at each location while maintaining a safe distance to prevent contact and damage when the heating rotator expands.
Solution Approach 2:
The patent implements feedback by using distance sensors to detect the actual separation gap between each separation member and the heating rotator. The drivers then adjust the separation members based on this feedback to maintain the optimal separation gap, preventing both sheet jams and contact damage.
3Device complexity
If the positions of separation members are fixed, then the device structure is simple, but the separation gap varies when sheets of various sizes pass through, causing sheet jams
Solution Approach 1:
The patent applies segmentation by dividing the separation member system into multiple independently adjustable units. Each separation member can be individually positioned using its own driver, allowing the system to adapt to varying thermal expansion conditions at different locations without requiring a complex overall restructuring.
Solution Approach 2:
The patent replaces manual or mechanical adjustment systems with automated electro-mechanical adjustment using drivers and distance sensors. This substitution enables precise and consistent separation gap maintenance while keeping the adjustment mechanism relatively simple and easy to control.
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 effectively prevents sheet jams by maintaining consistent separation gaps and preventing damage to the heating rotator, ensuring reliable operation across different sheet sizes and thermal conditions.
Implementation Method 1
a heating unit configured to heat the first rotator such that the heat is transferred to the sheet passing through a contact portion between the first rotator and the second rotator. Therefore, the toner is melted and fixed onto the sheet.
Implementation Method 2
when the heating rotator is thermally expanded, the separation member comes into contact with the heating rotator
Data Source
AI summary
A fixing device is configured to fix a toner image to a sheet by heat and includes: a heating rotator; a pressurizing roller contacting with the heating rotator; a heater configured to heat the heating rotator such that the heat is transferred to the sheet passing through a contact portion between the heating rotator and the pressurizing roller; a plurality of separation claws configured to separate the sheet from the heating rotator such that the sheet passing through the contact portion is not caught in the heating rotator, the separation claws being provided opposite to the heating rotator; and an adjustor configured to adjust positions of the separation claws relative to the heating rotator such that distances between the separation claws and the heating rotator are equal to each other.