Movable Heat Shield for Fixing Rotary Body Overheating
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face overheating issues due to non-conveyance spans on the fixing rotary body, leading to increased manufacturing costs and potential thermal deformation of heat shields, which interfere with surrounding components.
Innovation Solution
A movable heat shield is interposed between the heater and the fixing rotary body, with a primary shield portion and a recess, allowing it to rotate between a shield position to protect the non-conveyance spans and a retracted position to avoid overheating, while an overheating suppressor shields the heat shield from direct heat exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat shield is used to shield the non-conveyance span from the heater, then overheating of the fixing rotary body is prevented, but the heat shield is exposed to direct heat and undergoes thermal deformation
Solution Approach 1:
An overheating suppressor is introduced as an intermediary component between the heater and the heat shield. This suppressor reflects heat away from the heat shield, preventing the heat shield from being directly exposed to high temperatures while still allowing the heat shield to perform its function of protecting the non-conveyance span from overheating.
2Productivity
If multiple heaters are used to correspond to different recording medium sizes, then heating efficiency is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
A movable heat shield is implemented that can dynamically adjust its position along the circumferential direction of the fixing rotary body. This dynamic adjustment allows a single heater to effectively heat different spans of the fixing rotary body corresponding to different recording medium sizes, replacing the need for multiple fixed heaters while maintaining heating efficiency.
3Manufacturing precision
If the heat shield is made movable to adjust shielding position, then heating precision is improved, but device complexity increases
Solution Approach 1:
The heat shield is designed with a movable mechanism that allows it to adjust its position in the circumferential direction. This dynamic positioning enables precise control over which spans of the fixing rotary body are shielded from heat, allowing a single heater to efficiently heat different areas corresponding to various recording medium sizes while maintaining simple overall device structure.
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 overheating of the fixing rotary body, reduces manufacturing costs by eliminating the need for multiple heaters, and minimizes thermal deformation of the heat shield, enhancing the reliability and performance of the fixing device.
Implementation Method 1
a fixing rotary body heated by a heater... the fixing rotary body heated to a predetermined fixing temperature... together heat and melt toner of the toner image
Implementation Method 2
A heat shield is movable in a circumferential direction of the fixing rotary body and interposed between the heater and the fixing rotary body to shield the fixing rotary body from the heater
Implementation Method 3
An overheating suppressor is interposed between the heater and the heat shield to shield the heat shield from the heater
Implementation Method 4
the recording medium passing through the nip draws heat from the fixing rotary body
Data Source
AI summary
A fixing device includes a fixing rotary body and a heater disposed opposite the fixing rotary body. A heat shield is movable in a circumferential direction of the fixing rotary body and interposed between the heater and the fixing rotary body to shield the fixing rotary body from the heater. An overheating suppressor is interposed between the heater and the heat shield to shield the heat shield from the heater. The heat shield includes an intermediate portion spanning in the circumferential direction of the fixing rotary body and movable between a shield position where the intermediate portion is disposed opposite the heater directly and a retracted position where the intermediate portion is disposed opposite the heater via the overheating suppressor.