Fixing Belt Heating Segmentation for High-Speed Toner Fixability
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the fixability of toner images is deteriorated due to variations in melting behavior of toner particles, especially at high process speeds, as the fixing belt's temperature is not consistently maintained, leading to inadequate heat transfer and fixation.
Innovation Solution
The image forming apparatus incorporates a fixing unit with a first heating rotator contacting the inner peripheral surface of the fixing belt and additional second heating units on both the inner and outer peripheral surfaces, ensuring consistent heating across the belt's circumference and downstream areas, thereby maintaining optimal temperature for fixability even at high process speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single heating rotator is used to heat the fixing belt, then the device complexity is reduced, but the temperature uniformity and fixability deteriorate at high process speeds
Solution Approach 1:
The heating system is segmented into multiple independent heating units: a first heating rotator that contacts the inner peripheral surface of the fixing belt, and second heating units positioned at multiple locations including the outer peripheral surface. This segmentation allows each heating unit to independently contribute to temperature maintenance, ensuring uniform heating across the entire fixing belt circumference and improving fixability reliability at high process speeds.
Solution Approach 2:
Multiple heating units are combined to work simultaneously on the fixing belt. The first heating rotator and second heating units operate together to maintain the fixing belt temperature, creating a redundant heating system that ensures consistent temperature distribution even during high-speed operation, thereby resolving the contradiction between device simplicity and fixability reliability.
2Productivity
If the process speed is increased to improve productivity, then the output increases, but the temperature consistency and fixability deteriorate
Solution Approach 1:
The multiple heating units are positioned to provide preliminary and continuous heating to the fixing belt before and during the toner fixation process. This preliminary action ensures that the fixing belt reaches and maintains the optimal temperature range even at high process speeds, preventing temperature drops that would otherwise occur during rapid operation and ensuring consistent fixability.
Solution Approach 2:
The heating system provides continuous thermal energy to the fixing belt through multiple heating units operating simultaneously. This continuity of useful action ensures that the fixing belt temperature is consistently maintained throughout the high-speed operation cycle, eliminating temperature fluctuations and ensuring reliable fixability regardless of process speed increases.
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 stable and enhanced fixability of toner images by maintaining the fixing belt's temperature close to the set temperature, reducing variations in toner melting and improving image formation quality at high speeds.
Implementation Method 1
a first heating rotator that is provided so as to contact an inner peripheral surface of the fixing belt in the nip portion and heats the fixing belt
Implementation Method 2
a second heating unit that is provided on at least one of an inner peripheral surface side and an outer peripheral surface side of the fixing belt, and heats the fixing belt separately from the first heating rotator
Implementation Method 3
a pressurizing rotator that forms a nip portion between the fixing belt and the pressurizing rotator by pressurizing an outer peripheral surface of the fixing belt
Implementation Method 4
the paraffin wax has a melting temperature of 60° C. to 80° C.
Implementation Method 5
a binder resin containing an amorphous resin and a crystalline resin; wherein the toner has a volume average particle diameter of 6 μm to 9 μm, a shape factor SF1 of 140 or more, and a toluene-insoluble portion of 25% by weight to 45% by weight; the paraffin wax has a melting temperature of 60° C. to 80° C.; and an absolute value of a difference between a melting temperature of the crystalline resin and a melting temperature of the paraffin wax is 10° C. or less
Data Source
AI summary
An image forming apparatus includes a fixing unit including a fixing belt, a pressurizing rotator that forms a nip portion between the fixing belt and the pressurizing rotator by pressurizing an outer peripheral surface of the fixing belt, a first heating rotator that is provided so as to contact an inner peripheral surface of the fixing belt in the nip portion and heats the fixing belt, and a second heating unit that heats the fixing belt separately from the first heating rotator, wherein a toner to be used has physical properties described in the specification and includes an amorphous resin, a crystalline resin, and paraffin wax having a melting temperature of 60° C. to 80° C., and an absolute value of a difference in a melting temperature between the crystalline resin and the paraffin wax is 10° C. or less.