Fixing Device with Multi-Zone Heating for Thermal Control
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Solution Overview
Problem
Image forming apparatuses face challenges with long warm-up times, energy inefficiency, and inconsistent fixing control due to inadequate thermal capacity and size mismatches between set and actual sheets, leading to defective fixing and potential damage to the fixing device.
Innovation Solution
A fixing device with a rotatable fixing member heated by multiple heat sources and temperature sensors to control temperature distribution, reducing operating speed when sheet size discrepancies are detected to prevent overheating and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thin fixing belt with low thermal capacity is used to reduce energy consumption and warm-up time, then energy efficiency improves, but thermal capacity becomes inadequate causing temperature drops during high-speed printing
Solution Approach 1:
The fixing belt is divided into multiple heating zones with independent heat sources (first heating unit near leading end, second heating unit near trailing end, third heating unit at intermediate position), allowing localized temperature control to maintain thermal capacity during high-speed operation without increasing overall energy consumption excessively
Solution Approach 2:
Different portions of the fixing belt are provided with different heating capabilities - the leading end portion receives heat from the first heating unit, the trailing end portion from the second heating unit, and intermediate portions from the third heating unit, ensuring each region maintains appropriate temperature for its specific function
2Loss of time
If SURF technology with ceramic heater is used to shorten warm-up time, then warm-up time reduces, but only the nip portion is heated leaving other parts cool causing defective fixing
Solution Approach 1:
The heating system is segmented into multiple independent heating units positioned at different locations along the fixing belt - the first heating unit near the leading end, the second heating unit near the trailing end, and the third heating unit at an intermediate position - ensuring comprehensive heating of the entire belt surface rather than just the nip portion
Solution Approach 2:
The heating approach transitions from localized point heating (SURF) to distributed linear heating along the entire length of the fixing belt, adding spatial dimensionality to the heating coverage and ensuring uniform temperature distribution across all portions of the belt
3Productivity
If the fixing device operates at high speed to increase productivity, then productivity improves, but thermal capacity deficiency causes temperature drops during continuous printing
Solution Approach 1:
The first heating unit is positioned to heat the leading end portion of the fixing belt in advance before sheets arrive, and the second heating unit heats the trailing end portion, ensuring the entire belt is pre-heated to the required temperature before high-speed printing begins, preventing temperature drops during continuous operation
Solution Approach 2:
Multiple heating units operate simultaneously and continuously along the entire length of the fixing belt, maintaining constant heat supply during high-speed printing to compensate for heat loss and prevent temperature drops, ensuring uninterrupted effective fixing action
4Manufacturing precision
If multiple heat sources heat the entire fixing member to improve temperature distribution, then fixing quality improves, but the fixing device may be overheated when sheet size mismatches occur causing damage
Solution Approach 1:
Temperature sensors are positioned to detect temperatures at specific locations (leading end portion and intermediate portion) and provide feedback to the control unit, which adjusts the operation of heating units accordingly - when sheet size mismatch is detected and sheets do not pass through certain heating zones, the control unit reduces or stops operation of those heating units to prevent overheating and damage
Solution Approach 2:
The operating states of the heating units are dynamically adjusted based on detected sheet size - the control unit determines whether each heating unit should operate at full power, reduced power, or remain off based on real-time conditions, transitioning from static to dynamic control to prevent overheating while maintaining fixing quality
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
The solution effectively reduces warm-up times, enhances energy efficiency, and prevents damage by ensuring consistent temperature control across the fixing member, even when sheet sizes differ, thereby improving fixability and productivity.
Implementation Method 1
a plurality of heat sources to heat each area of the fixing member in a longitudinal direction thereof
Implementation Method 2
a plurality of temperature sensors to detect temperature of the fixing member or the pressure member in each heating area heated by the plurality of heat sources
Implementation Method 3
A heat source 3 inside the conductive pipe 2 heats the endless belt 1 via the conductive pipe 2
Data Source
AI summary
A fixing device in an image forming apparatus includes a rotatable fixing member; a plurality of heat sources to heat each area of the fixing member in a longitudinal direction thereof; a pressure member configured to contact the fixing member and forming a nip in association with the fixing member; a nip forming member disposed inside the fixing member and opposite the pressure member to form a fixing nip; a temperature controller to detect temperature at each area of the fixing member and control the temperature via lighting control performed by the heat sources; and a plurality of temperature sensors to detect temperature of the fixing member or the pressure member in each heating area heated by the plurality of heat sources. When a sheet size set by the image forming apparatus and an actually conveyed sheet size are different, operating speed of the device is adjusted.