Fixing Unit Pressure Adjusting Mechanism for Wear Reduction
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Solution Overview
Problem
The repeated butting and separating actions in image forming apparatuses, particularly in the fixing units of electrophotographic systems, lead to issues such as plastic deformation of compression coil springs, reduced adhesive force due to stress in the thickness direction of adhesives, and abrasion of members, which can cause instability in temperature detection and safety element operation, and affect the quality and lifespan of the fixing unit.
Innovation Solution
The image forming apparatus incorporates a pressure adjusting mechanism that adjusts the frequency of pressure release based on cumulative usage, with different frequencies before and after a predetermined threshold is reached, thereby reducing the number of butting and separating actions and minimizing wear and tear on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pressure of the fixing unit is automatically released when jam detected or in sleep mode, then the recording material can be removed easily and deterioration of fixing member is prevented, but the compression coil spring undergoes repeated extension and contraction leading to plastic deformation
Solution Approach 1:
The pressure adjusting mechanism transitions from a static constant pressure state to a dynamic state where pressure is adjusted based on operational conditions. The control unit dynamically switches between applying full pressure during active operation and reducing/releasing pressure during idle or jam conditions, optimizing both operational ease and component durability
Solution Approach 2:
The pressure parameter of the fixing unit is changed based on operational state. During active image formation, full pressure is applied. During sleep mode or jam detection, the pressure parameter is reduced or released. This parameter change prevents spring fatigue while maintaining fixing effectiveness during operation
2Shape
If the heater is separated from the heater holder by pressing members, then the heater can be positioned, but the support state changes causing unstable temperature detection and safety element operation
Solution Approach 1:
An adhesive layer is introduced as an intermediary between the heater and heater holder. This adhesive layer provides continuous support and stable thermal contact, ensuring reliable temperature detection and safety element operation while allowing the pressing members to perform their positioning function without causing instability
3Shape
If adhesive is used between heater and heater holder to prevent separation, then heater positioning is maintained, but repeated butting and separating actions cause adhesive peeling due to stress in thickness direction
Solution Approach 1:
The pressure parameter is dynamically changed based on operational state. During active operation, full pressure is applied for proper fixing. During sleep mode or jam detection, pressure is reduced or released, minimizing the stress cycles on the adhesive layer and preventing fatigue-induced peeling while maintaining heater positioning
4Adaptability or versatility
If pressure adjusting mechanism repeatedly applies and releases pressure, then jam handling and sleep mode functions are achieved, but the compression coil spring becomes plastically deformed and unable to apply intended pressure
Solution Approach 1:
The pressure adjusting mechanism operates periodically based on operational needs - applying pressure during active image formation and releasing/reducing pressure during sleep mode or jam detection. This periodic action pattern allows the system to maintain necessary functionality while minimizing cumulative stress on the spring, extending its service life
Solution Approach 2:
The pressure parameter is dynamically adjusted based on operational state. By reducing or releasing pressure during idle periods and jam conditions, the stress cycles on the compression coil spring are minimized, preventing plastic deformation while maintaining the ability to apply full pressure when needed for image formation
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 approach decreases the frequency of pressure release after reaching the cumulative usage threshold, reducing the issues associated with repeated butting and separating actions, such as plastic deformation and adhesive force reduction, thereby extending the lifespan and maintaining the quality of the fixing unit components.
Implementation Method 1
a compression coil spring used in the pressure adjusting mechanism is plastically deformed by the repetition of extension and contraction
Implementation Method 2
an adhesive interposed between the heater and the heater holder, the following phenomena may occur. Specifically, stress is applied in the thickness direction of the adhesive, which is a direction in which the heater and the heater holder are separated from each other, to decrease the adhesive force of the adhesive
Implementation Method 3
a thermistor for detecting the temperature of the heater
Implementation Method 4
a heat roller method that uses a fixing roller housing a halogen heater
Data Source
AI summary
An image forming apparatus includes an image forming unit to form an image on a recording material and a fixing unit. The fixing unit fixes the image formed on the recording material to the recording material. The fixing unit includes a heating member and a pressing member to form a nip portion to nip and convey the recording material with the heating member. The fixing unit further includes a pressure adjusting mechanism to apply pressure to the nip portion and release or reduce the applied pressure. If a parameter for a cumulative usage of the fixing unit is a first value, frequency of release or reduction of the applied pressure is a first frequency. If the parameter for the cumulative usage is a second value greater than the first value, the frequency of release or reduction of the applied pressure is a second frequency lower than the first frequency.