Image Forming Apparatus Cooling Control via Variable Air Opening
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Solution Overview
Problem
Existing image forming apparatuses face challenges in managing temperature increases in out-of-sheet-path portions of the fixation nip, leading to issues like fixation failure and 'hot offset, due to limitations in cooling fan revolution speed adjustments.
Innovation Solution
An image forming apparatus with an air feeding portion that includes a fan, duct, and adjusting member to control air flow to non-sheet-passing areas, allowing for varying air feeding operations based on sheet width and temperature thresholds, thereby regulating temperature effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cooling fan revolution speed is increased to cool the out-of-sheet-path portions, then the temperature of out-of-sheet-path portions is reduced, but the fan revolution speed range is limited and cannot properly deal with both moderate and severe temperature increases
Solution Approach 1:
The cooling control is segmented into two independent parameters: fan revolution speed and air outlet opening amount. This segmentation allows the system to independently adjust each parameter to achieve precise cooling control. The air outlet opening is divided into first opening (for moderate temperature increase) and second opening (for severe temperature increase), enabling differentiated cooling strategies for different thermal conditions.
Solution Approach 2:
The system dynamically adjusts both fan revolution speed and air outlet opening amount based on real-time temperature detection. The control is not static but adapts to varying thermal conditions by changing the degree of opening and fan speed, providing flexible and versatile cooling control across different operating scenarios.
2Device complexity
If a fixed fan revolution speed is used, then the device structure is simple, but it cannot adapt to different temperature increase conditions (moderate vs severe)
Solution Approach 1:
The cooling control function is segmented into two controllable elements: fan revolution speed and air outlet opening amount. This segmentation transforms a single-parameter control system into a two-parameter control system, enhancing adaptability without excessive complexity. The air outlet is further segmented into different opening positions (first opening and second opening) corresponding to different temperature conditions.
Solution Approach 2:
The system changes multiple parameters simultaneously - both the air outlet opening amount and fan revolution speed are adjusted based on temperature conditions. This multi-parameter control approach allows the system to adapt to different temperature scenarios (moderate vs severe increases) while maintaining a relatively simple overall structure.
3Temperature
If the cooling air amount is increased to prevent hot offset, then the temperature of out-of-sheet-path portions is controlled, but fixation failure may occur due to excessive cooling
Solution Approach 1:
The cooling air is directed specifically to the out-of-sheet-path portions through the air outlet, providing localized cooling without affecting the sheet-path portions. This local quality approach ensures that only the areas needing cooling (out-of-sheet-path portions) are cooled, while the fixation areas (sheet-path portions) maintain their required temperature, preventing fixation failure.
Solution Approach 2:
The system precisely controls the cooling parameters (air outlet opening amount and fan revolution speed) based on detected temperature conditions. By adjusting these parameters proportionally to the temperature increase severity, the system achieves accurate temperature control that prevents both overheating (hot offset) and excessive cooling (fixation failure).
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 solution effectively stabilizes the temperature of out-of-sheet-path portions, preventing fixation failure and 'hot offset, while maintaining the instant startup characteristic of film heating type fixing devices.
Implementation Method 1
an air feeding portion for feeding air to a non-sheet-passing area of at least one of the heating member and the back-up member
Implementation Method 2
a fixing portion, including a heating member and a back-up member for cooperating with the heating member to form a nip, for fixing the unfixed toner image on the recording material by heating the recording material having the formed unfixed toner image in the nip
Data Source
AI summary
An image forming apparatus includes a fixing portion, including: a heating member and a back-up member forming a nip; and an air feeding portion for feeding air to a non-sheet-passing area of at least one of the heating member and the back-up member, the air feeding portion including a fan for feeding the air, a duct, including an opening, for guiding the air fed from the fan through the opening to the non-sheet-passing area, and an adjusting member for adjusting an opening amount of the opening. The apparatus executes a first air feeding operation with a first opening amount and a first rotational frequency of the fan and a second air feeding operation with a second opening amount and a second rotational frequency, when the fixing portion fixes the images on sheets having the same widths.