Fixing Device Cover Adjusts Airflow Gap for End Region Cooling
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Solution Overview
Problem
Conventional image forming apparatuses experience temperature increase issues at the end portions of the fixing device due to uneven heat distribution, leading to inefficient cooling and potential complications in design.
Innovation Solution
An image forming apparatus with a housing containing a fan and an air passage, featuring a heat unit with a central and end region, and a movable cover that adjusts its distance from the heat unit to optimize airflow and cooling, ensuring effective temperature regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a fan and an assembly for changing opening width are incorporated to restrain temperature increase at the end region, then temperature control is improved, but device complexity increases
Solution Approach 1:
The patent combines the temperature control function with the existing cover structure by making the cover movable between first and second positions. This integrates the cooling control mechanism into the cover rather than adding a separate assembly, thereby reducing device complexity while maintaining effective temperature restraint at the end region.
Solution Approach 2:
The cover is designed to be movable between different positions (first position for normal operation, second position for cooling) rather than being fixed. This dynamic adjustment allows the system to control airflow and temperature at the end region without requiring complex mechanical assemblies, simply by repositioning the existing cover.
2Temperature
If the cover is positioned close to the heat unit (first position), then cooling effect is enhanced, but heat loss from central region increases
Solution Approach 1:
The movable cover enables localized cooling at the end region by adjusting its position, while the central region maintains its heat through the same cover structure. When the cover is in the first position, it provides cooling at the end; when in the second position, it preserves heat at the central region. This local differentiation of thermal management resolves the contradiction between enhanced cooling and heat loss prevention.
Solution Approach 2:
The dynamic repositioning of the cover allows the system to adapt to different thermal management needs. By moving the cover between positions, the system can selectively apply cooling where needed (end region) while maintaining heat where required (central region), thus managing energy loss effectively.
3Productivity
If successive printing is performed with sheets narrower than the heat unit axial length, then productivity increases, but temperature accumulation at end regions occurs
Solution Approach 1:
The system employs periodic action by alternating the cover position based on printing conditions. During normal successive printing, the cover remains in the first position for optimal cooling. When temperature accumulation is detected or predicted (after certain printing cycles), the cover moves to the second position to cool the end region, then returns to the first position. This periodic adjustment maintains productivity while preventing temperature accumulation.
Solution Approach 2:
The movable cover system provides feedback-based temperature management. The system monitors thermal conditions at the end region and adjusts the cover position accordingly. When temperature accumulation occurs during successive printing with narrow sheets, the cover moves to the second position to increase cooling, then returns to the first position when temperature is controlled, creating a feedback loop that maintains both productivity and temperature 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
The solution effectively restrains temperature increase at the end regions of the fixing device, simplifying the apparatus design while maintaining efficient cooling, thereby improving operational stability and reducing the risk of overheating.
Implementation Method 1
a housing (100) comprising a fan (106), and a wall portion (107) forming an air passage in communication with the fan (106)
Implementation Method 2
a fixing device comprising: a heat unit provided in the air passage and extending in an axial direction, the heat unit comprising a heater
Data Source
AI summary
A fixing device includes: a heat unit extending in an axial direction and comprising a heater, the heat unit having a central region in the axial direction and an end region outside of the central region; an opponent member to face the heat unit; and a cover positioned opposite to the opponent member with respect to the heat unit. The cover has: a central cover portion positioned to face the central region and spaced away from the central region by a reference distance; and a side cover portion positioned to face the end region and movable between a first position providing a first distance from the heat unit and a second position providing a second distance from the heat unit, the first distance being not more than the reference distance, and the second distance being greater than the reference distance.