Heating Device Shutters for Fixing Belt Temperature Control
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Solution Overview
Problem
In fixing devices used in electrophotographic image forming apparatuses, the excessive temperature rise at the longitudinal end portions of the fixing belt leads to durability issues and problems like offset and jam during transitions from small-sized to large-sized sheet printing, due to uneven heat distribution.
Innovation Solution
The implementation of a heating device with a housing that includes a pair of openings and shutters, which can be rotated to control airflow and prevent excessive temperature rise at the non-sheet passage portions by using a blower fan and air ducts to dissipate heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a planar heater is used to heat the fixing belt from the inside, then the sheet can be heated effectively and toner images can be fixed, but the longitudinal end portions (non sheet-passing portions) of the fixing belt experience excessive temperature rise
Solution Approach 1:
The heater is divided into multiple heating zones along the longitudinal direction of the fixing belt. Each heating zone corresponds to a specific section of the belt, allowing independent temperature control. The non-sheet passage portions are equipped with separate heating elements that can be controlled separately from the sheet passage portions, preventing excessive temperature rise in areas where sheets do not pass through.
Solution Approach 2:
Different sections of the fixing belt are provided with different heating characteristics. The sheet passage portions have heating elements optimized for heating sheets, while the non-sheet passage portions have heating elements with reduced power or different thermal properties to prevent excessive temperature rise. This local differentiation ensures that each area receives appropriate heat treatment for its specific function.
2Reliability
If the temperature of the end portions rises excessively, then the durability of the fixing belt deteriorates, but maintaining uniform temperature across the entire belt increases energy consumption
Solution Approach 1:
The heating system is segmented into multiple independently controllable zones. By dividing the heater into sections corresponding to different functional areas of the fixing belt, energy can be supplied selectively to only those zones that require heating at any given time, rather than heating the entire belt uniformly. This reduces overall energy consumption while maintaining reliability in critical areas.
Solution Approach 2:
Instead of applying full heating power across the entire fixing belt, the system applies partial heating action only to the necessary portions. The non-sheet passage portions receive reduced or no heating when sheets are not present, while sheet passage portions receive appropriate heating only when sheets are being processed. This partial action approach minimizes energy waste while ensuring reliability where needed.
3Productivity
If small-sized sheets are continuously printed, then productivity is maintained, but the temperature at the end portions rises excessively causing offset and jam
Solution Approach 1:
The heating system is divided into zones that can be independently controlled based on sheet size and position. When small-sized sheets are continuously printed, the segmented heating system can adjust the temperature in non-sheet passage portions separately from sheet passage portions, preventing the excessive temperature rise that causes offset and jam while maintaining high printing speed.
Solution Approach 2:
The heating system dynamically adjusts temperature distribution based on real-time operating conditions. When small sheets are continuously fed, the system increases heating in sheet passage portions to maintain productivity while simultaneously reducing or modulating heating in non-sheet passage portions to prevent excessive temperature rise and associated problems like offset and jam.
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 prevents excessive temperature rise at the end portions of the fixing belt, reducing the risk of offset and jam, and ensures consistent heat distribution for various sheet sizes, thereby enhancing the durability and performance of the fixing device.
Implementation Method 1
a blower fan and air ducts to dissipate heat effectively
Data Source
AI summary
A heating device includes a heating rotator, a pressing rotator, and a housing. The heating rotator extends in a longitudinal direction and is configured to heat a sheet. The pressing rotator extends in a longitudinal direction and is configured to press against the heating rotator to form a nip with the heating rotator. The housing houses the heating rotator and the pressing rotator. The housing includes a pair of openings and shutters. The pair of openings face both end portions of the heating rotator in the longitudinal direction of the heating rotator. The shutters are configured to rotate about an axis extending in the longitudinal direction of the heating rotator to open and close the pair of openings.