Fixing Device Heat Absorption Roller Periodic Contact Control
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Solution Overview
Problem
The existing fixing devices face issues with temperature uniformity and contamination due to the heat-relieving roller not contacting the pressing roller when the non-sheet-passage-part temperature does not reach an eligible temperature, leading to inefficient cleaning and potential contamination of the pressing roller.
Innovation Solution
A fixing device with a heat absorption rotatable member that can move to and away from the first rotatable member, a counter to track the number of operations without contact, and a controller to determine when to initiate contact for a predetermined period during non-fixing processes, ensuring proper cleaning and temperature uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the heat-relieving roller is spaced from the pressing roller at the beginning of a job to reduce start-up time, then the start-up period is reduced, but the cleaning function is not executed and the pressing roller becomes contaminated
Solution Approach 1:
The heat-relieving roller is brought into contact with the pressing roller periodically after a predetermined number of fixing operations, as controlled by the control unit. This periodic contact ensures the cleaning function is executed at regular intervals while maintaining spacing during active fixing operations to reduce start-up time.
Solution Approach 2:
The control unit determines in advance when the heat-relieving roller should contact the pressing roller based on the count of fixing operations. This preliminary determination ensures the cleaning function is activated before contamination becomes severe, balancing start-up performance with maintenance of cleanliness.
2Reliability
If the heat-relieving roller is continuously contacted to the pressing roller to maintain cleaning function, then the pressing roller remains clean, but the start-up time increases due to heat absorption
Solution Approach 1:
The system uses periodic contact rather than continuous contact between the heat-relieving roller and pressing roller. The control unit manages the contact timing based on the number of fixing operations, allowing the pressing roller to heat up quickly during start-up while still providing regular cleaning intervals.
Solution Approach 2:
The positional relationship between the heat-relieving roller and pressing roller is made dynamic rather than static. The roller moves from a spaced position during fixing operations to a contacted position for cleaning, with the control unit determining the timing of this transition based on operational count.
3Speed
If the thermal capacity of the pressing roller is reduced to reduce start-up time, then the heating speed increases, but the temperature uniformity deteriorates in non-sheet-passage areas
Solution Approach 1:
The heat-relieving roller serves as an intermediary that absorbs excess heat from the pressing roller's non-sheet-passage areas. When contacted, it acts as a heat sink to uniformize the temperature distribution, allowing the pressing roller to have reduced thermal capacity while maintaining temperature uniformity during operation.
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 ensures the cleaning function of the heat absorption rotatable member is executed effectively, maintaining the cleanliness of the pressing roller and reducing temperature differences between sheet-passage and non-sheet-passage areas, thereby improving the overall performance and longevity of the fixing device.
Implementation Method 1
a heat absorption rotatable member configured and positioned to absorb heat from said first rotatable member by contacting said first rotatable member
Data Source
AI summary
A fixing device includes first and second rollers forming a nip for fixing a toner image on a sheet; a heat absorption roller for absorbing heat from said first roller by contacting said first roller; a moving mechanism for moving said heat absorption roller to and away from said first roller; a counter for counting a number of continuously executed fixing process operations without said heat absorption roller contacting said first roller; a controller for determining, based on an output of said counter, whether to carry out an operation of a mode in which said heat absorption roller is contacted to said first roller by said moving mechanism and is rotated for a predetermined period, during non-fixing process period.