Fixing Device Heater Block Segmentation for Thermal Control
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Solution Overview
Problem
In image forming technologies, continuous printing of sheets of the same width leads to excessive temperature rise in non-paper passing regions, causing irreversible performance deterioration such as warpage of heaters, deterioration of fixing belts, and expansion of conveying and pressing rollers.
Innovation Solution
A fixing device with temperature sensors disposed in non-paper passing regions to detect excessive temperature rises, and a processor that temporarily stops electric power supply to affected heater blocks or reduces printing rate to maintain temperature within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous printing of sheets of the same width is performed, then productivity is improved, but excessive temperature rise occurs in non-paper passing regions causing performance deterioration
Solution Approach 1:
The heater is divided into multiple heater blocks (first heater block, second heater block, etc.) along the width direction. Each heater block can be independently controlled based on the sheet width being printed. This segmentation allows the system to activate only the necessary heater blocks for the current sheet size, preventing excessive temperature rise in non-paper passing regions while maintaining productivity through continuous printing capability.
Solution Approach 2:
The system dynamically changes the operational parameters of the heater by adjusting which heater blocks are activated based on sheet width detection. When a narrow sheet is detected, only the corresponding central heater block is activated, reducing the overall heating area and preventing temperature excessive rise in side regions. This parameter adaptation resolves the contradiction between continuous printing productivity and component durability.
2Temperature
If the heater region outside the sheet passing region is continuously heated, then the sheet can be adequately heated for fixing, but irreversible performance deterioration such as warpage and expansion occurs
Solution Approach 1:
Different regions of the heater are assigned different functional qualities based on sheet width requirements. The heater blocks corresponding to the sheet width are activated to provide necessary heating, while heater blocks in non-paper passing regions remain inactive. This local quality differentiation ensures adequate sheet heating while preventing dimensional instability and warpage in the heater and rollers.
3Measurement precision
If temperature sensors are added to monitor non-paper passing regions, then excessive temperature rise can be detected, but device complexity increases
Solution Approach 1:
Temperature sensors are strategically placed in specific non-paper passing regions (e.g., first non-paper passing region, second non-paper passing region) corresponding to different heater blocks. This segmented sensor placement allows precise temperature monitoring where needed without unnecessarily increasing device complexity across the entire system. Each sensor monitors its specific region and triggers control actions only when that region exceeds temperature thresholds.
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
Prevents performance deterioration by controlling excessive temperature rises, ensuring stable operation of heaters, fixing belts, and rollers, thereby extending their lifespan and maintaining image forming apparatus efficiency.
Implementation Method 1
a heater that is disposed to be in contact with an inner surface of the belt and is divided into a plurality of heater blocks in a width direction of the belt
Implementation Method 2
a first temperature sensor that is disposed in a non-paper passing region for a maximum sheet which can be fixed in the heat generation block
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A fixing device includes an endless belt, a heater in contact with an inner surface of the belt and divided into a plurality of heater blocks in a width direction of the belt, a pressing member positioned to face the heater with the belt interposed therebetween and configured to press a conveyed sheet against the belt and the heater, a temperature sensor disposed in each of at least half of the heater blocks, and a processor. The processor selects heater blocks based on width and position of the conveyed sheet to form a heat generation block, controls power supplied to the heater blocks so that a temperature of the heat generation block is within a predetermined temperature range, and selects the temperature sensor disposed in a heater block having a non-paper passing region and control an excessive temperature rise in the non-paper passing region.