Rotatable Light Shield for Fixing Rotator Temperature Uniformity
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face issues with uneven temperature distribution along the fixing belt, leading to overheating at lateral ends, which can result in degradation and reduced performance, especially when handling sheets of varying sizes.
Innovation Solution
The implementation of a nip formation pad with a thermal conductor sandwiched between the base and the fixing rotator, along with a rotatable light shield that shields the fixing rotator from light emitted by the heaters, helps in maintaining consistent temperature by absorbing and distributing heat effectively, and adjusting the heating pattern based on sheet size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heaters are used to heat the fixing rotator, then the fixing temperature is improved, but uneven temperature distribution and overheating at lateral ends occur
Solution Approach 1:
The patent introduces a light shield that selectively blocks light from the second heater at specific locations (lateral ends of the fixing rotator) while allowing light from the first heater to reach those areas. This creates a non-uniform light shielding arrangement that compensates for the natural tendency of lateral ends to overheat, achieving more uniform temperature distribution across the fixing surface.
2Stability of the object's composition
If a light shield is introduced to block light from the second heater, then temperature uniformity is improved, but device complexity increases
Solution Approach 1:
The light shield acts as an intermediary element between the second heater and the fixing rotator. It selectively intercepts light from the second heater at strategic locations without interfering with the overall heating function. This intermediary component enables temperature uniformity control while maintaining a relatively simple structural implementation.
3Measurement precision
If the second heater is disposed at a location where it can be readily screened, then temperature control precision is improved, but heating efficiency may be reduced
Solution Approach 1:
The light shield implements partial blocking of light from the second heater, rather than complete blocking. By strategically positioning the light shield to block light only at specific locations (lateral ends) where overheating occurs, the system achieves precise temperature control without excessively reducing overall heating efficiency. The first heater continues to provide comprehensive heating coverage.
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 consistent temperature across the fixing belt, preventing overheating and maintaining performance across different sheet sizes, thereby extending the lifespan of the fixing device and improving print quality.
Implementation Method 1
a first thermal conductor sandwiched between the base and the fixing rotator at the fixing nip and having a first thermal conductivity greater than the basic thermal conductivity of the base
Implementation Method 2
A rotatable light shield moves to a shield position where the light shield is interposed between the second heater and the fixing rotator to shield the fixing rotator from light emitted from the second heater
Implementation Method 3
A first heater is disposed opposite an inner circumferential surface of the fixing rotator to heat the fixing rotator
Implementation Method 4
A second heater is disposed opposite the inner circumferential surface of the fixing rotator to heat the fixing rotator
Data Source
AI summary
A fixing device includes a nip formation pad pressing against a pressure rotator via a fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator. The nip formation pad includes a base and a first thermal conductor sandwiched between the base and the fixing rotator at the fixing nip and having a first thermal conductivity greater than a basic thermal conductivity of the base. A first heater and a second heater are disposed opposite an inner circumferential surface of the fixing rotator to heat the fixing rotator. A rotatable light shield moves to a shield position where the light shield is interposed between the second heater and the fixing rotator to shield the fixing rotator from the second heater. The second heater is disposed at a location where the light shield screens the second heater more readily than the first heater.